Why my screen turned black?

So my phone fell, and the entire screen went black.

At first it was a crack, the next day the bottom half was flashing and couldn't see the bottom of my screen but this awfully strong flashing light. Then two days later it went black, and couldn't hear my phone ring or anything even tho I had charged for couple days but then I tried rebooting it (power button with lower voice button) and I will only see a thin line in the middle of the screen!

What needs to be fixed or replaced?