Did it ever work?
Make sure you are plugging your speakers into the proper output. The out jack is typically green unless you have some fancy sound board. There may also be more than one sound card - perhaps one on the motherboard and another slot based card. Try both.
Make sure sound isn't muted - look for the little speaker icon at lower right in your startup tray. Double click on it and make sure the "mute" button isn't checked, they try turning up the volume on the various outputs.
You can also check in "Control Panel - Sounds and Audio Devices". Look at the Hardware tab and make sure you see what you expect, then select it and "Properties" to make sure it is enabled.
One last thing, if you are using powered speakers, make sure they are plugged into a wall outlet....