[Hindsight]

Those sound like Component Video cables. There is one red, blue and green, right?
You also need the white and red RCA audio cables with those; which do not affect your video though.

I would try using the coaxial, s-video or HDMI video outputs to your DVD to the TV, to see if those work. It will tell you a lot.

If it is the comp. cable, buy one in the bargain bin somewhere. They're all the same.

Also, make sure you have the correct video input selected on the TV, but it sounds like you have the right one. Take a close look at the connectors on the cables, DVD and TV input to see if there is obvious damage.