Also know as a Factory Reset. It will delete all of your data, configuration. Putting it back to when you initially got it.

I'm not too sure, haven't actually done it. But I don't think that it'd be any sort of 'recovery' in the event that you modify a system file.

1. Power down the pone.
2. Press and Hold: D Pad Left + Power.
3. Wait for the ** WIPE USERDATA **
4. Allow it to reboot, and you're back to square one!