In order to hard reset a LG C199, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
LG C199 device will be brought back to the default configuration of a brand new device.
1. Hold down the Power button until the phone turns on.
2. Open Main menu and enter Reset Settings > Master Reset. Confirm by pressing Left Softkey.
3. Type in the (by default) 0000 code.
4. Congrats, your phone should now reset and restart.