LG Optimus LTE Tag hard reset
To reset your LG Optimus LTE Tag hard reset phone to factory settings and erase all the data on your phone, touch Menu > Settings> Privacy > Factory data reset > Reset phone.
Resetting the phone does not erase any system software updates you have downloaded or any files on your microSD card,
such as music or photos. If you reset the phone in this way, you are prompted to re-enter the same information that you did when you first started Android.
You can use LG Mobile Support tool to repair your LG cell phone, after download select menu Customer Support > Recovery Phone