Horizontal line on the top of the screen

I have a MacBook Pro model A1708, and since this morning when I woke up, there was suddenly a black line on top of my screen. I already googled many solutions such to simply restart your MacBook or to shut down the computer and pressing various keys such as the combination of the Option-command-P-R keys or only the shift key. however none of it works.

Could someone pls tell me what I should do?