Lumia 1520 - Why wouldn't the lower 3/4 of my screen respond?

[WPCentral Question]

I have a Lumia 1520 and my screen works. No cracks or anything. But it would not respond to swipes or touches from the lower 3/4. Neither the start, back or search buttons would respond. My Volume buttons and power button works too but camera button hasn't been working for a while now (another nuisance). I have tried resetting but that doesn't work. Any ideas??