WARNING! When you factory reset your phone, all the personal information stored on the device’s internal memory will be deleted. This includes contacts and media files, ringtones, apps etc. Furthermore, all settings will be restored to factory values, but data located on the SIM and SD cards will not be affected.

NOTE: You can check this thread for a guide on how to back up data before a factory reset. You can also check this thread for instructions on restoring data.

Factory Reset via Settings:

1. Launch “Settings”
2. If necessary, go to “Tab view” and access the “General” tab
3. Scroll to “Phone Management” and tap “Backup & reset”
4. Tick or clear the boxes next to “Automatic restore” and “Back up my data”
5. Tap “Backup account” and select an account
6. When ready, tap “Factory data reset”
7. Optionally you can choose whether to “Erase SD Card” too
8. When ready, tap “Reset phone”
9. If necessary, enter your lockscreen PIN / passwords
10. Tap “Delete all” > “Reset” to confirm

Factory Reset via Recovery:

NOTE: In case your device crashes, freezes, or otherwise prevents you from resetting it using the method above, alternatively you can reset your phone from the Recovery menu, which can be accessed by performing the following.

1. First turn the phone off
2. Next, press and hold “Power” and “Volume down” simultaneously
3. At the LG logo, quickly release and re-hold “Power”
4. At the “Factory data reset” screen, release all the keys
5. Next, press “Volume down” repeatedly to navigate to and highlight “Yes”
6. Press the “Power” key to confirm the selection
7. When prompted to “Erase all user data and restore default settings” highlight “Yes” and press “Power”