well, i would say boot into rrecovery by making the phone off either power button, or remove and replace battery.
next, you will need to press and hold in order: power/end call, call, and volume down.. this should boot recovery mode.
lastly, use the red scroll device to go to reset facory defaults or factory recovery, use common sense while looking. select with clicking and use arrow back button to go back to recovery main, then reboot to system. easy as pie.