Completely reset a Symbian Series 60 mobile

Normal Reset (*#7780#) : Restores ini files from rom but preserves user data (photos, 3rd party apps etc)

Deep Reset (*#7370#) : This reformats completely the C: drive. All applications and files stored on this drive will be lost and clean default files will be rewritten.

12345 is the default confirmation code if you haven’t changed it.