|S-Video does not carry Audio, only Video.|
To get Audio you need an Audio cable from the Laptop Line Out to the TV. The TV will probably have three RCA connectors, White, Red and Yellow. The Red and White are Audio left and right and the Yellow is for composite video.
You need a cable with a 3.5 mm Stereo jack on one end the two RCA plugs on the other. They are common and easy to get hold of. Any computer or audio shop will sell them.