Macbook Pro Screen Black

Having trouble here. My macbook pro “15 screen is entirely black, aside from the very top.

I don’t know why this is happening. I have a Dell external monitor connected. Its done this before, but usually only for a few seconds until the screen returns to normal. Nothing is showing on the external monitor. I’ve unplugged the monitor but nothing helps. Device is charged.

Id appreciate any help, this is frustrating.