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 lets turn your phone to it's back cover and hold down power button to power off device.
2. Now wait few seconds and press power button with volume down button combined
3. Hold those buttons untill you will see LG logo on your screen, then you can release them.
4. Then you should be seeing on your screen Recovery mode menu.
5. Now using your volume buttons go to wipe data/factory reset and select with power button.
6. And just like that you finished hard reset process, congratulations.
Doing a factory reset has some advantages for a few purposes.
One of the big ones is wanting to remove all Data from the device.
This is handy if you plan on giving the device to someone else and don't want to give them your contacts or any other information.
In some circumstances it can even be handy to just start over especially if you have some minor issues and you assume the issues are Data related.
If rooted its a great way to wipe the Data and Cache area's to prepare to change the ROM of the device.