For the lg xenon, you can lock your screen but you can also lock your entire cell phone so no one can go through it. You simply go to the menu then settings then the "Phone" button then "Security".
After that you will see the Phone lock and when you can lock it. You can also change the code. The code should be 0000.
After that you will see the Phone lock and when you can lock it. You can also change the code. The code should be 0000.