On rare occasions, and through no fault of your own (unless you jailbreak your iPhone or iPad), your iDevice might end up in recovery mode. This typically happens after an update to a new firmware or when you are trying to restore a backup.
Fix your iPhone or iPad in recovery mode
Essentially, you'll find that your device won't turn on, or it will cycle the boot process but never reach the home screen. You might even see the iTunes logo with a USB cable pointing at it on your screen.
If you follow Apple's method of exiting recovery mode (below), you will lose all the data on your device: it will be restored to the most recent backup on your computer.
While we can't vouch for it as we haven't tried it, there's a utility called TinyUmbrella (for Mac and Windows) which claims to get your iDevice out of recovery mode without erasing any data, so you shouldn't lose any photos, videos, contacts and so on. Other applications are availble, such as RecBoot for Mac OS.
When you run these utilities, they offer an option to enter or exit recovery mode - it's a simple case of clicking the button with your iPhone or iPad already connected to your PC via a USB cable.
Another trick to try, if you have a jailbroken device and are having problems, is to power off the device as in step 2 below. Then turn it on by holding the power button and the volume up button. As soon as the screen lights up (and before the Apple logo appears) release the power button but continue holding the volume up button. This turns off add-ons and tweaks and - hopefully - should allow your iPhone or iPad to boot without the mods running and - crucially - without losing any data.
If you have a recent backup of your non-jailbroken device, follow these steps:
Putting your iPhone or iPad into recovery mode
(if your device is already in recovery mode, scroll down to step 7)
NOTE: Recovery mode is not DFU mode. Recovery mode is where your iOS device loads iBoot, a bootloader which allows your iPhone or iPad to be restored using the existing or newest firmware. DFU mode bypasses the standard restoring procedures and lets you do more advanced things like downgrading the firmware - we won't cover this here.
1. Make sure your device is unplugged from your computer (this should be the computer that you use to sync your iPhone / iPad). You can leave the USB cable connected to your PC or Mac, though.
2. Turn off your iPhone / iPad. Press and hold the power button on the top edge until a slider appears. Slide it to power off your device. If the slider doesn't appear (because your iOS device has frozen up) then hold the power and Home buttons down until the iPhone or iPad turns off.
3. Ensure your device has a decent amount of charge. Leave it plugged in to the mains for 10 minutes or so if you see the flat battery icon in the next step.
4. Hold down the Home button and connect the USB cable: this should cause your iPhone or iPad to turn on. Keep holding the Home button until you see the iTunes and USB cable images on screen, then release the button.
5. In iTunes (launch the application if it isn't running), you should see a message saying an iPhone (or iPad or iPod touch) has been found in recovery mode. You can follow the instructions to restore it from a backup on your computer.
Getting your iPhone or iPad out of recovery mode
6. If your device is already in recovery mode, connect it to your computer and run iTunes. You may have to hold the Home button while you connect the USB cable.
7. iTunes should detect the device is in recovery mode and offer to restore it from a backup. All personal data, apps and settings will be removed from your iPhone or iPad and it will be restored to the most recent backup, so some data might be lost if you haven't backed up for a while.