A Hard Reset reverts a phone to its original settings and a clean OS (Operating System) removing all data and information added to the cell phone by the mobile phone user.
In essence a Hard Reset erases everything from the phone and puts the phone back to like new condition as though it’s brand new right out of the box.
1. First thing you will have to do is turn off your device.
2. Wait few seconds and press and hold volume down button with power button to start hard reset process.
3. When you will see LG logo appearing on your screen you can safely release the buttons that you held.
4. Now on your screen you should see recovery mode menu.
5. Using your volume buttons to move highlighted area down to wipe data/factory reset option press Power button to select and finish the hard reset.
6. And it's done! You know how to perform hard reset on you LG Optimus 4X HD.