First make sure your speakers are plugged into the correct jack on your computer or sound card. They should be plugged into the "green" jack. If this doesn't work, go to START, CONTROL PANEL, and select "Sounds and Audio Devices" Click on "Audio" and see if your sound card appears in the "Default" window. If not, you will need to re-install your sound card. If you don't know how to do this you might get a friend who is computer "wise" to look at your bias settings to see if the sound part of your motherboard is turned on.
Hope this helps
Bruce, June 2008