Its in the users manual. Pg.137 and 138
But here you go..
With the phone turned off, press and hold the VOLUME DOWN, TALK/SEND, and END/POWER buttons
Release the VOLUME DOWN, TALK/SEND, and END/POWER buttons.
Press the VOLUME UP button to restore the operating system to the factory default configuration,
press the VOLUME DOWN button to restore the factory default configuration and remove any operator
customization, or press any other button to cancel the reset.
Now hit Thanks !