tonmasProbably a loose or faulty display cable connecting the screen to the motherboard.
eh probably not, usually that would distort most of or the entire screen.
Likely what's wrong here is you probably have a faulty ribbon cable (or 2) that controls power to that particular area of your screen. Only way to really confirm that though is to basically near fully disassemble your laptop, remove all the casing around the display power on the display and peel off the top layers of the display to verify that the back-light is lit. Do not actually peel apart the LCD screen though. The outer layer of the display will be a thin transparent sheet of plastic and the next layer will likely be the LCD screen, the LCD screen is the layer that you actually see what is being displayed. Note you will have a hard time seeing whats on the screen without a back light, but you can use a flashlight to do quick checks to see if this is the layer being affected. If you still see the black area you normally see you know for sure that the problem is power getting to those pixels (especially if you display a black image and the normal black area is still darker), if while moving the lcd screen the black area suddenly changes or goes away get smaller etc, it likely means the ribbon cable is ok but it doesn't have good contact. Repairing this part is a pain in the ass and usually not worth it imo.
just for the sake of clarity this is where i think your issue is.
https://youtu.be/axmZJBRGYn4?t=5m43s
Honestly you would be better off finding a similar sized laptop display and replacing your old one with that one, just getting a new laptop, or hook up a standalone monitor via HDMI / VGA or whatever.
-edit-
Just realized that the ribbons I'm referring to control power only in vertical strips. Horizontal lines like you have mean your display is full on fucked.