LG Optimus 4G LTE hard resetusing buttons
Turn off the phone.
Press and hold both Volume down + HOME + Search buttons + POWER on your LG Optimus 4G LTE phone.
Factory reset wipe data.
or factory reset via menu
To reset your LG Optimus 4G phone to factory settings and erase all the data on your phone, touch Menu > Settings> Privacy > Factory data reset > Reset phone.
You can use LG Mobile Support tool to repair your LG cell phone, after download select menu Customer Support > Recovery Phone