How to fix a shadow on my 40inch samsung lcd tv?

i recently bought a 40in lcd tv from walmart, it was reduced by 50 percent because it was a return and had some minor scratches on the casing around the screen. the people at walmart told me it was returned because a speaker went bad but they replaced it and nothing else was wrong, well being such a good price i brought it home just to find out it has a large dark spot in the screen in the shape of c of the far right hand side. it isnt damaged on the outside that i can tell but i dont really know the story behind the tv. i have looked up the problem on the web and tried several things people recommended for other people with similar problems but none of them seem to help any in my case. can someone Please help me?? i dont have any money to get it replaced or repaired so any suggestions would be very much appreciated. also if u want pictures if that would help just email me at xm3x4@yahoo.com thank u