Can you try attaching an external monitor to the laptop, see if you still see the same problem ?
If an external monitor works OK that would probably mean the laptop screen has a problem. There are a few small components around a laptop screen that help it to work correctly, but unless you are confident about fixing it yourself, it's going to need looking at.
I have replaced an inverter on an Asus laptop, cost about £50 , but shop wanted another £70 to fit it for me. Decided to have a go myself, very fiddly, but got there in the end. If someone can ID your problem and tell you which part you need, you might be able to fix it yourself. Best of luck with it.