First I would try updating the drivers for the display and see if that resolves it.
If that doesn't do it, then (if the device is not under warranty) you may want to open it up and make sure the displays ribbon cable isn't dented, pinched, loose, damaged, etc. If it is you may need to replace it.
Another option to try is turn off the laptop. Connect an external monitor, turn on the external monitor and then turn on the laptop. Can you see things fine on the external monitor? If yes, then the laptops display may be going and need replacing. If you can't see anything, or still have the problem, on the external monitor then your graphics card may be going.
NOTE: If the device is still under warranty, you do not want to do anything to it that would void that warranty. In that case you should contact the manufacturer about a repair or replacement.