Before you buy a new cell phone or new tablet, please try the following procedure to repair your device. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.!
LG Optimus L9 P760 hard resetUsing the Optimus LG L9 P769 hard reset
1 Turn the phone off.
2 Press and hold the following keys at the same time for 8 seconds: Volume Down Key + Home Key + Power/Lock Key .
3 Your device will perform a factory reset and reboot.
Caution: If you perform a hard reset, all user applications and user data will be deleted. This cannot be reversed.
Remember to back up any important data before performing a hard reset.
To reset your LG Optimus L9 P760 Android hard reset phone to factory settings and erase all the data on your phone, Select Settings → Back up and reset→ Factory data reset → Reset device→ Delete all.
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
Go to Support > Mobile Phone Support > Select the Model (LG-P769).
LG L9 SAFE MODE
To recover your phone when malfunctioning.
1 Turn off your phone and reboot. When you see the (T-Mobile) animation press and hold the Volume Down Key . Your main screen will then be displayed with
the words "Safe mode" in the lower left corner.
2 From the Home screen, tap the Menu Key and tap App settings.
3 Tap one of the available tabs at the top of the screen and select the application
you wish to uninstall.
4 Tap Uninstall and OK to confirm.
5 After uninstalling the application, turn off and reboot your phone.