With phone turned OFF, press the Home key and Power button simultaneously. The device will power on. Keep holding the buttons downuntil Recovery screen (exclamation mark in triangle with android figure) appears.
Press the Search key.
Touch wipe data/factory reset then touch Ok.If the touch screen is not functioning, utilize the Volume key (up/down) to highlight and the Camera key to select.
Touch Yes--delete all user data and touch OK.This will bring back the device to factory settings.
Power off your device.
Next press and hold Volume Up + Volume Down + Power button.
If you see Android logo, then press Home key.
Then select option "wipe data/factory reset" using Volume buttons to scroll, and Power button to confirm operation.
Now choose from the menu option "Yes -- delete all user data".