You may also want to try hitting CTRL + SHIFT + WIN + B to try and reset your graphics driver as another possible fix.
Now if you can see fine on the external monitor, then your attached display, or the ribbon cable that connects it, are your problem. You will have to check those both to see if they are the issue. This, obviously, will require opening up the device. So if it is under warranty, contact the manufacturer instead. As opening it could void your warranty. If you don't feel comfortable opening it up yourself (and it isn't under warranty) then try a local tech.
I have tried opening up the laptop, then the screen.
It turned out that the tape that was meant to be connected at the back of the screen was disconnected and when I connected it the screen was working fine.