The following steps are intended for the LG Rumor Reflex S.

Press the Home button at the bottom of the screen. 

Tap Main Menu.

Tap Settings.

Tap Reset/Delete.

Tap Keep Existing Lock Code.

(Note: The default lock code is the last 4 digits of the mobile number.)

Tap Reset Phone.

Tap Reset.

Once the phone restarts, it will need to be set up for the first time.