A hard reset, also known as a factory reset or master reset, is the restoration of a device to the state it was in when it left the factory.
All settings, applications and data added by the user are removed.
The term is often heard in reference to smartphones and tablets but laptop and desktop computers, as well as most other electronic devices, can usually be restored to factory conditions.
1. First step of the whole process is turning off your device.
2. Now press and hold power button with home button and volume down button at he same time.
3. After a moment there should be LG logo, thats when you can release the buttons.
4. Few seconds later and you will get into recovery mode screen.
5. Use your Volume keys to navigate and power button to select option.
6. Now scrool to wipe data/factory reset option and select it.
7. The end, your device will restart and will work like new after that.