IPhone 4 screen turned white?

My phones screen turned white and won't go off. I can see the top bar that says I'm connected to Wi-Fi and the battery. But when I press the home screen it doesn't go off. I tried turning it on and off but nothing happens. The volume still goes up and down and it let's me take screenshots… But the white screen won't go away. Plus it doesn't lock. It just goes tinted but never full lock. Someone help fast please!

Its a blank