From Factory Reset
Samsung Galaxy S2 Factory Reset
- Turn off the phone.
- Press and hold down Volume Up + Home + Power buttons at the same time.
- Release all buttons when you see SGS2 Logo.
- Android system recovery will be loaded then.
- Select wipe data/factory reset. (Volume buttons to go up or down, select with Home button)
- Select Yes — delete all user data.
- Finally, select reboot system now.