Why isnt my phone displaying anything?

I accidentally dropped my phone once. After I picked it up, everything worked fine, except the screen. I could use my pattern to unlock, which means hat the touch was working but the lights were off.

I thought that was a display issue and thought that it needs a replacement.

I bought one, tested it but nothing new happened. There was nothing on the display.

Am worried if my motherboard is gone, or is there anything that needs a technicians assistance.