My first suspect would be the video cable. If you can (with it powered off), disconnect & reconnect the cable and then try rebooting the laptop.
The ribbon cable (usually located on the back side of the LCD). Sometimes just reconnecting it will do the trick. If not I would suggest to replace the cable before any other parts (it should be relatively inexpensive.)
The connectors are fairly fragile, so be gentle with it or watch a YouTube video on LCD replacement for your model (i'd skip to the relevant parts)