Please install the 'LauncherPro' application from Google Play and then follow the steps below:
Once installed, press your LG's Home and Start buttons and then select ‘LauncherPro’ on the window that appears.
Now, press any empty space on the home screen and don't let go until a new window opens. Select Direct Access.
Press 'Activities' and then wait for a few seconds.
Scroll down the list of options and select 'com.lge.hiddenpersomenu'.
Type the name the system prompts you for to gain direct access.
To access the hidden menu, press the direct access you've just created.
Select ‘Network Lock’. Here you can unlock your LG.