to format your LG Optimus S mobile phone follow the tips:
- switch your mobile off , if it is not responding remove the battery from the mobile phone.
- press and hold the volume down+home button+power button , wait for the android recovery menu to appear .
- choose wipe data/Factory reset using the volume down for scrolling and the home button to select it.
- the choose yes- delete all user data using the home button
- then after the factory reset finished , choose reboot system now using the home button
note :please backup your mobile phone before starting the process , since all of your mobile data will be lost after the reset.