I am 95% certain you need to replace the LCD based on your description. However lets do a few things to rule out all possibility of it being any thing else. Move the upper part of the laptop that holds the lcd backwards and forwards from the hinge, while observing the display. If things get better or worse by doing that it could be the video data cable or a bad connection to that cable. Hook up an external monitor up if the picture is good on an external monitor. Then it is either the LCD or the video data cable. If the picture is similar on the external monitor the it is most likely either failing video memory or GPU. Please let us know more after you have tried these test and we will help you get the part that needs replaced and provide a guide to replace it.

Sounds like you need to replace your LCD. Go under the Apple icon in the upper left hand corner to "about this Mac", more info, >Hardware > Graphics/Displays. Get the information on your screen.

Also please give the last three letters of your serial number so we know exactly which machine you have. (located in the battery compartment). This will allow directing toward the correct guide.

What about this!

I had this same problem, but after 1.5 years of daily use (never been dropped). My solution is a little ghetto, but works. I drilled two 2.9mm holes where the two missing hinge screws previously attached; right through the aluminum case of the laptop. Then I popped everything back into place and secured the hinge to the lid by thru-bolting with two M3 screws, locwashers and nuts. I used 10mm long screws that I had on hand, but 8mm would have been better.

While you have it open , reglue the broken off screw attachement posts , but also also reinforce all the screw posts on the mid frame with a little Gorilla glue. Once one post breaks, extra stress is placed on the remaining posts which break over time with routine use.

Adjust the left hinge nut so it is not so tight.