Master Resetting Using Through The Settings Menu:

WARNING: master resetting your device will bring the handset to original factory settings. This will result in deletion of personal data stored on the handset's internal storage, including apps, contacts, ringtones, photos and more. Note: content stored on the SD and SIM cards will not be affected. To perform a master reset:

  1. If necessary, back up your data
  2. While on the home screen, press the "Menu" button on your device
  3. Select "System settings"
  4. Under "Personal", tap "Backup & reset"
  5. Tap "Factory data reset"
  6. Press "Reset phone" and tap "Erase everything"
  7. Review the warning message and tap "OK"

Master Resetting Using Hardware Buttons:

WARNING: much like with the soft reset method, hardware master resetting will erase all the data stored on your phone's internal storage. Use this method if your device is frozen, can't boot etc.

  1. If possible / necessary, back up the data stored on the internal memory
  2. Power off your handset
  3. Press and hold the "Power", "Home" and "Volume down" keys at the same time, for roughly 8 seconds
  4. Once the "Factory hard reset" screen appears, release the aforementioned buttons
  5. Press the "Power" button to confirm the reset. The process will start automatically

Booting Up in Safe Mode:

Safe mode allows you to turn on your smartphone with all the third-party apps being disabled. This method can be useful if a third-part app is causing issues with your device, such as the inability to boot properly and uninstall it. To enable safe mode:

  1. From the home screen, press and hold the "Power" button
  2. Tap and hold "Power off"
  3. Review the "Reboot in safe mode" screen and tap "OK". Note: once the device restarts, the "Safe mode" message should appear in the lower-left corner of the screen
  4. Uninstall any third-part apps that are causing problems

Disabling Safe Mode:

  1. While viewing any screen, press and hold the "Power" button
  2. Tap "Power off and restart" and tap "OK" to confirm

See More: LG Optimus F3: Master Reset; Booting in Safe Mode