iPhone 5 - Is on, but nothing shows up on screen

Hi guys, I was wondering if anyone had this issue or knows how I can resolve this..

My iPhone 5, for no apparent reason, just went completely black. There's nothing on the screen, but the phone is still on. When I try to use Siri, etc, I can hear it, but I can't see anything.

When I press the power button, I can see the backlight turn on, but everything still black.

Any suggestions?