Suddenly the screen turns into that :

[Oussaber]

Look at the file attached.

 

[BarredOwl]

Time to visit or call Apple. Use that AppleCare.

 

[Oussaber]

I don’t have apple care, here in Morocco we have just resellers and it’s not a physical hardware damage.

 

[jav6454]

Hardware fault, you need to use warranty claim on it.

 

[poorcody]

I'm assuming the black lines appear not just on the background picture?

Did you try switching out of dark mode?

 

[Oussaber]

I'm assuming the black lines appear not just on the background picture?

Did you try switching out of dark mode?

Yes, I did but still the same problem. Dark lines are multiplying.
[doublepost=1566906953][/doublepost]

Hardware fault, you need to use warranty claim on it.

What if I don’t have one?

 

[maflynn]

What if I don’t have one?

Then you will have to pay for the repair or buy a new computer if you don't want to (or cannot) get it repaired.