Hard Reset (Factory Reset)
If you forget your lock sequence and backup PIN, you will have to perform a hard reset to gain access to your phone.
Performing a hard reset deletes all of your user data, which includes pictures, videos, and music saved to your internal memory. Please make sure to back up your information prior to performing a hard reset.
Turn the phone off.
Press and hold the following keys at the same time: Volume Down Key
+ Power/Lock Key 
on the back of the phone.Release the Power/Lock Key
only when the LG logo
is displayed, then immediately press and hold the Power/Lock
Key again.Release all keys when the Factory hard reset screen is displayed.
Press the Volume Down Key
to highlight Yes, then press the Power/ Lock Key to continue.Press the Volume Down Key
to highlight Yes once more, then press the Power/Lock Key to confirm.Your phone will perform a factory reset.
To cancel and reboot your phone, select the No (Exit) option.