Warning: You will lose all your personal data, contacts, emails, sms...etc.
Turn the phone off.
Press and hold VOLUME UP and Home (center) button
Press Power until the phone vibrate
Wait until you see the Android logo then release all the buttons.
Select Wipe data / Factory reset with VOLUME DOWN, press Power (right hand-side)
Select YES -- delete all user data with VOLUME DOWN and then press Power
After format, press Power again to reboot phone. (Select reboot system now)
Samsung Master Reset:
CAUTION: A "master reset" changes the phone settings back to default. This process will erase all contacts, downloaded settings, and downloaded applications (ringtones, wallpapers, graphics, etc). This process cannot be undone.
Enter *2767*3855# from the standby screen. (You may need to remove the SIM before it will allow you to type the code in)
