Was your phone rooted when you gave it to your friend? If not, did you friend try and root it for you? First thing I'd do is see if you can get into recovery. Pull the battery out, then put it back in. Now hold the vol. up + vol. down + power button. The screen will flash the splash screen twice then release the power button but keep holding the vol. buttons until you get into the recovery menu. If you get that far, clear the cache and perform a data reset.