Could be Old or bad plugs, could also be the Plug Wires, I would start with changing the Wires & Plugs, but as Oldturkey03 stated to try first is the best option. Good luck Chris

It could be just the connection that is loose, You could try to search on Youtube for your Laptop model and see if you have any luck, I did that for my Laptop screen that I broke and thanks to Youtube I was able to replace it fairly easily and cheaper of course. I actually have another Laptop that has the same problem you described but I have not bothered to repair it since I have an External Monitor hooked up to it. Good Luck Chris

You may want to check out this site for something like that : http://www.icracked.com/