Windows has slowed to a crawl. Applications won’t run. Your firewall won’t update or uninstall itself. System Restore hasn’t helped; neither have your assorted clean-up and antimalware programs. Only one option remains: reinstall Windows and start from scratch. But it’s a time-consuming job, and your PC could be unusable for a day or more. You could even lose all your data.

While we usually advise against reinstalling Windows unless you absolutely must (and certainly not because a tech support person thinks it could solve a complicated problem, such as getting you off the phone), sometimes it’s necessary.

Here’s our guide to making the process as safe and painless as possible.

Windows installation toolkit

Before you begin you’ll need a recovery tool. If you’re using the version of Windows that came preinstalled on your PC, that tool is probably in a hidden partition on the hard drive. That partition has the information necessary to restore the hard drive to its factory condition.

If your PC is a few years old, the recovery tool may instead be on one or more CDs or DVDs that were supplied in the box. The manual should say what kind of recovery tool came with the PC and how to access it.
If you’ve upgraded Windows since you bought the machine, the upgrade disc is now your recovery tool.

If you can’t find a recovery disc and the PC has no hidden partition, contact the manufacturer to see what it can do for you. Also see How to install Windows without the restore disc.

Following the installation, you’ll have to reinstall any programs you want to continue using. Collect the original discs or downloaded installation files, plus any associated licence keys. You’ll need an external hard drive with a capacity at least as large as your internal drive. Finally, you’ll need time – at least a full day, if not more.

Back up everything

How to reinstal WindowsThings could go horribly wrong, so you need to make a backup of your hard drive and all the data stored on it. Use cloning software to turn the external drive into an exact copy of your internal hard drive. We recommend cloning the drive using EaseUs Todo Backup. Alternatively, you can create an image backup if you prefer.

A second backup of your data wouldn’t hurt. If you don’t have one already, create one using your regular backup program.
See our guide to the most suitable type of backup.

The Windows reinstall

The method for replacing a Windows installation depends on your recovery tool. If your PC came with a recovery partition, find the instructions for booting into the repair environment. Watch the screen as you turn on the PC; it might show a message such as ‘Press F10 for repair’. If it doesn’t, check the manual or search online for your PC.

If your recovery tool is a disc, boot up the PC from it and follow the prompts.

If your recovery tool is a Microsoft Windows disc, the tool will ask what kind of installation to perform. In Windows 7 or Vista, select the ‘Custom (advanced)’ option. In XP, at the ‘Welcome to Setup’ screen, press Enter to continue, rather than R for repair.

Once you have a fresh Windows installation, the hard work begins.

How to reinstal WindowsWindows will need updating. The patching will happen automatically, but you can launch Windows Update and let it take care of things if you want to get it out of the way.

You’ll have to reinstall at least some of your drivers. You can use the discs that came with your PC, printer, scanner and so on, or you can download newer versions from the web. Alternatively, you can install the drivers from the clone you made.

If you reinstalled Windows from a disc that came from your PC maker and it’s one that returns your hard drive to its factory condition, you probably have a lot of junk programs that you’ll want to uninstall.

Windows’ own uninstaller often leaves remnants behind. Use Revo Uninstaller or Total Uninstall. Both utilities run the program’s own uninstaller, then clean up the remainder.

Revo Uninstaller is free, but Total Uninstall does a better job with uninstalls that require a reboot. Revo Uninstaller doesn’t work with 64bit programs; Total Uninstall does.

Now that you’ve cleaned Windows of unwanted applications, you can reinstall the programs you do want. Start with your security software. Don’t try to install two programs at once, and always reboot the machine when prompted.

Once you have everything installed, take some time to make Windows your own. Choose a new wallpaper, change your power and screensaver settings and so on.

The final countdown

At this point, use backup software and an external hard drive to create an image of your internal hard drive’s contents. Should you ever need to reinstall Windows again, you can use this backup as your recovery tool. Again, we recommend EaseUs Todo Backup, although other good programs are available. Whatever you use, be sure to create an emergency boot disc with it.

Now it’s time to restore your data. If you used a Windows 7 retail or upgrade DVD, the data will be in a folder called C\Windows.old. If you used a manufacturer’s recovery tool, your files might be in a special folder, perhaps C\Backup. Otherwise, your data may no longer be on your hard drive.How to reinstal Windows

If such a folder exists on your hard drive, open it in Windows Explorer and navigate to its User (Windows 7 and Vista) or ‘Documents and Settings’ folder (Windows XP).

If the folder doesn’t exist, you’ll have to get it from the clone or image backup. Create a folder on the internal drive called Backup (in C\Backup). Plug in the external drive with the clone, then copy the contents of that drive’s User folder (Windows 7 and Vista) or ‘Documents and Settings’ folder (XP) to C\Backup. Unmount the external drive (using the System Tray’s Safely Remove Hardware tool). Leave Windows Explorer open to the C\Backup folder.

You should now have a Windows Explorer window open and displaying multiple folders, one for each user account. For convenience, let’s call this window the ‘backup location’.
Open a second Windows Explorer window and navigate to C\Users (Windows 7 and Vista) or C\Documents and Settings (XP). We’ll call this window the ‘proper location’, because it’s where your data will eventually be stored.

Open the User folders in both the backup and proper locations. You will see additional folders, mostly the same ones, inside each. Drag the folders you want to keep from backup to proper: Documents, Music, Pictures and Videos. Their names may be prefaced with ‘My’. Windows XP users needn’t worry about the lack of Music, Pictures and Videos folders; they’re in My Documents.

Don’t move AppData (Windows 7 and Vista) or ‘Application Data and Local Settings’ (Windows XP), although you probably won’t see these hidden folders anyway. Use your own judgment about the other folders, but be careful when merging any folders.

Eventually, you’ll be able to delete your backup or Windows.old folder. Wait a few months until you’re sure it contains nothing that you’ll need again.

Reformatting and restoring a PC isn’t fun. You have to back up your data, reformat the hard drive, install Windows, track down drivers, reload programs, restore your data and pull out clumps of hair over the things you neglected to save. But when your PC becomes so sluggish or malware-infested that no optimisation utility can help, sometimes the only remedy is a wipe and restore.

A clean installation is also an opportunity to return your PC to its factory state, and then to make it better. You’ll be able to implement a backup system to thwart future disasters, organise your files, cut performance-clogging security programs to a minimum and – above all – ensure that if you ever need to reformat and restore again, the process will be a lot easier.

Create a drive image

With a fresh copy of Windows perfectly configured and running smoothly, now is an ideal time to capture and preserve its state, just in case something goes awry later.
Create an image of your PC. This is in essence a full-system backup that contains all the extra stuff that gets added after a fresh Windows install. By making that image your restore source, you can save a lot of time if you ever need to perform another reinstall. Note, however, that an image won’t preserve your data.

Macrium Reflect is easy to use, and it can save your image file to an external drive, a network drive or disc. It’ll also build a bootable rescue disc for restoring the image, just in case you need to resurrect a seriously compromised PC.

Make a Linux partition

Linux operating systems are fast and robust, and stocked with all the software that most users need for everyday computing. Plus, many versions are free – and if your Windows install ever becomes too messed up to boot, you might be able to use Linux to save it.

This is the perfect time to create a dual-boot environment and devote a partition of your hard drive to Linux. When you’re finished, you’ll be able to choose Windows or Linux at every boot; it’s like turning one PC into two. And in the unlikely event that something goes wrong during setup, you can whip out the drive image you created earlier and restore the PC to its previous state.

We recommend Ubuntu, although countless other Linux versions are available. To install Ubuntu alongside Windows, you’ll need to download the operating system, burn it to a CD, create a partition within Windows, and then boot the Ubuntu CD and follow the instructions. See here for instructions.

Automate backups

You’re computing on thin ice. A malware attack or hard-drive failure might be just around the corner. The time has come to start making regular backups.

How to reinstal WindowsFirst, schedule a weekly full-system backup, using an external hard drive as the destination. The aforementioned Macrium Reflect works well, as it can create image files at scheduled times. However, consider buying the full version, which supports both differential and incremental backups. (The latter means the program adds only the files and data that have changed since the previous backup, a huge timesaver.)

Second, enlist an online backup service such as Carbonite or Mozy to save your crucial data to the cloud. We’re partial to the set-it-and-forget-it Mozy, which offers 2GB of free backup space, a highly automated utility, and the option of making a local backup too.

Organise everything

A re--stored PC gives you the rare chance to put everything in order: your files, your folders and even the desktop. Let’s start with the latter – no more leaving icons strewn across the desktop like clothes on the bedroom floor. Organise them with Fences, a free utility that turns cluttered desktops into tidy ones.

As for files, it’s always good to manually organise them as best you can, putting documents in one folder, photos in another, videos in a third and so on. But even if you have stuff spread out across hundreds of folders (and/or different drives), Windows 7’s Libraries feature makes finding what you need easy. It’s a much better approach than the age-old folder/subfolder system. The only trick is setting up Libraries properly (see

Slim down your security

How to reinstal WindowsMany PCs suffer from security software overkill, as users are tempted to install a firewall, antivirus and antispyware tools, a rootkit blocker and perhaps even a security suite on top of all that.
Take a simplified approach. Windows 7 has almost everything you need: a firewall, a spyware and pop-up blocker, an improved User Account Control system and a host of malware and phishing protections in Internet Explorer. Install Microsoft’s free Security Essentials and Web of Trust and you’ll have a well-protected PC. The only extra you might need is a spam filter, but most webmail services do a great job of filtering spam.

Install a better uninstaller

Many uninstalled programs leave traces – configuration files here, Registry entries there, and so on. This can make Windows slow down over a period of time.

What you need is a program that will remove every last vestige of any application. Try the aforementioned Revo Uninstaller or IObit Advanced Uninstaller, which offers a few perks that Revo lacks. One of them is batch uninstalling: an excellent timesaver that lets you select multiple programs to remove. IObit’s program is tiny (just 700KB) and portable, requiring no installation.

Make a Driver library

One of the biggest hassles in restoring a PC is tracking down drivers for all the attached components and peripherals. Even if you restore your machine from an image file, you might wind up with several drivers that are outdated.
Make device-driver backups a part of your regular backup regimen. Double Driver 4.1 (a free utility) accomplishes the task quickly and easily. It scans your computer, automatically detects and selects drivers that aren’t part of the operating system, then lets you back them up to a USB drive, a network folder or another portable storage device.

A quicker boot
Windows boots more slowly over time, as every program you install seems to insist on loading a piece of itself into the startup directory. Freeware utility Soluto can be used to analyse the software and services on your PC. It then lets you eliminate them, delay their startup or leave them alone. Soluto also offers recommendations, complete with statistics on what other users have done.