What settings need to be changed with adding a s-video

[Sue10]

I have installed a S-video from my PC to my TV, It was working fine then I detached it from tv so I could use my dvd player. I had done this before with no problem. This time however whe I reattached cable to tv all I got was a black screen. It is set to work on video on the tv. Do I need to reset it on my computer? If so what settings do I change?

 

[king smp]

need to know which operating system
what make and model of video card?