Recovering corrupt files
So far, we've talked about recovering accidentally deleted files but files can also be lost due to the disk’s file structure becoming corrupted. This could happen, for example, if a power failure occurred while a file was being written, leaving the disk directory in an unpredictable state.
As with accidentally deleted files, the data could all be there but Windows wouldn’t know where to find it. Often this sort of problem will manifest itself by Windows reporting some sort of error when you try to open a file or, conceivably, files could just have disappeared, even though you’re pretty sure you hadn't deleted them.
Software utilities are available to identify and correct this sort of error and you’ll find that some undelete products also offer the ability to recover from logical errors in the file system. While some pure undeletion utilities are free, you’ll often have to pay for those more fully featured products.
Some let you try before you buy, though. With RecoverMyFiles, for example, you can download the software in evaluation mode and run it to see what files it can recover from your disk. If you like what you see, you pay a fee to allow those files to be permanently recovered.
An exception to the rule that you get only what you pay is TestDisk which is free and open source and has earned a good reputation. It’s available for Windows, Linux and MacOS. Whatever software you use, though, as with pure undeletion packages, don’t install it to the offending disk as doing so could render your lost data permanently unrecoverable.
Also bear in mind that packages will differ in their ability to recover lost data. It would be a good idea, therefore, to try out several (so long as they have an evaluation mode which will show what they’re able to recover without actually writing to your disk) and choose whichever has the best success. Alternatively, if you don’t find any software that meets your needs, the option of using a data recovery service is always available, but it isn't necessarily a cheap option.
Hard disk failure
Having dispelled the myth that deleted and corrupted files are lost forever, we now come to the problem that all PC users dread – a hard disk failure. This could manifest in several ways but generally Windows won’t start, even in Safe Mode, and turning on your PC might be accompanied by unhealthy clicking noises. What you stand to lose, therefore, isn’t just a few of your treasured files but the entire contents of the disk.
It’s commonly suggested that hard disks can be repaired by putting them in the freezer. While this has been known to work, bringing the drive back to life for just long enough to extract the most important files, it’s effective only for certain very specific types of fault. Often it won’t work and attempting it might just prove to be the last straw for your ailing disk. Our recommendation, therefore, is that you don’t attempt this nor any other DIY repair.
Instead, as soon as you suspect a hardware failure, turn off your PC immediately and make contact with a data recovery company such as Kroll OnTrack. These companies have vast stocks of parts that they are able to swap in their clean room to restore a disk to a working state. Once this has been achieved they’ll copy all the data they can recover to encrypted removable media such as a USB drive. This will work for failures of most parts of the disk including the electronic circuit boards, the motor and the read/write head, but there’s a limit to what can be achieved.
As the part on which the data is actually stored, if the platter is scratched or shattered it’s normally game over although, fortunately, this is rare. As always, it pays to shop around before deciding which company to use and it’s also a good idea to choose a company that will diagnose the problem for free. As guidance, though, if you were to go to Kroll OnTrack, you’d pay a fixed fee of £599 including VAT as a consumer whereas charges for businesses depend on exactly what’s involved.
Although data normally can’t be recovered if a hard disk’s platter is scratched, the same isn’t necessarily true of optical discs such as CDs and DVDs. So long as the scratch is only in the plastic protective layer and not the underlying data storage layer, chemical formulations and mechanical polishing machines are available to help repair your disk. Digital Innovations’ SkipDR, for example, costs £14 from PC World.