There are two different techniques of hard reset for LG Optimus P500. You can try it with the use of the device key or by using the settings menu .
What are we gonna show you here is hard reset using the device key. This method is useful when your device is locked with a code or unlock pattern and you forgot the code or unlock pattern or when you power your device it hangs on logo only and you can’t go to the settings menu. You can also use this if you simply just want to restore your device back to its original factory settings without going to the settings menu.
Steps to hard reset LG Optimus One P500
1. Turn off the device. If the phone is frozen, pull the battery out and insert it back again.
2. Hold the Home and Volume Down button.
3. Press and hold the Power button while holding the Home and Volume Down button until the phone turns on.
4. Follow the on-screen instructions to hard reset the phone handset.