Wipe and Restore your iPhone / iPod

Warning! this will erase all data on your device

If you havn't tried already, you can restart your device.

If you find, after restarting your device, that you are still having problems (the device freezes on loading screen) and you are unable to get iTunes to recognise the attached device, then there is a way to "hard restore" your device.

Hold the Home button while reconnecting your iPhone / iPod to your computer. Keep it held until you see an image appear on the screen (probably the iTunes symbol, depending what version you're running).

This will put your device in recovery mode. You will then be able to restore the device through iTunes