Sound on computer, what to look for?

My parents had a similar problem With their Dell Dimension 4600. Nobody knew what was wrong with it. It could be a number of things with your case. What kind of computer do you have number one? Then you go to start, then all programs, then click accessories, then Entertainment and click on volume Controller. When you open it see if the main volume output is muted. Their will be a box with a check box with it labed mute. If that does not work it might be your media card. That is what hahappenedith my parents coComputerI used a spare part to get it working. If you have ititunesn your computer try clicking on itunes. Itunes uslally dectects problems with your media before it opens it will say their their is no media dectectiong located and will not be able to playback. Hopefully this helps