In order to hard reset a LG G7120, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
LG G7120 device will be brought back to the default configuration of a brand new device.
1. Power up the phone by press-holding the Power button.
2. Is it on? Okay then: enter Menu > Settings > Reset settings > Master reset.
3. Enter the security code into the phone - 0000 by default - and confirm with left softkey.
4. Voila, done.