I know it's possible cause I've done it before… But I needed to know how to do it again. There's a key combination while its starting so that you can just reset all factory settings.It's called recovery mode. NOT RESTORE MODE. I can't find it on google.It resets your home screen, all settings and removes your passcode.
Added (1). It DOES exist, I haveDONE IT BEFORE, but it was an not jail broken iPod touch 2nd gen, figured it'd be the same type of thing for iPhones though.
>>> How to boot this iPhone into recovery mode?