One possibility is that the video ribbon cable that goes thru the hinge area will sometimes have cracked conductor trace lines due to opening/closing the lid too much. Another possibility is that the video ribbon connectors simply need to be re-seated a half dozen or so times at the screen and mainboard to clean the connections. Either way, the screen bezel and keyboard will have to be removed to access this ribbon cable. 

The laptop model and number should affixed to a label on the bottom of the machine. Video ribbons are pretty cheap but you need to know what you have.

Jack E/NJ