Hi!
Your problem could have a number of causes and we will need to work towards excluding the unlikely ones. First, update your post with the specs of your laptop.
Now. The problem could either be the GPU that went bad because of overheating or the display cable, that could also have gone bad due to overheating.
To see which components is not working as expected, connect the laptop to an external display. If you still see the stripes on the external monitor, then it's the GPU that needs to be replaced. If not, it might be the display cable.