Can you be more specific with the problem?

It could be in a few areas. It could be the speakers themselves. It could be the software you're using to play music. It could be your sound drivers. It could be the controller in to which you have your speakers plugged.

If you can't access the volume control panel applet, try opening it from the system tray (at the bottom-right corner of your screen. It's the one with the speaker icon).

Do you have a sound card? If you do, it could be that it is faulty.

Press Win+Break on your keyboard, it should bring up the System Properties screen. Then click Hardware and then on Device Manager. Then look for the "Sound, video and game controllers" section. If you see a yellow exclamation mark or a red cross or a question mark superimposed upon any list item under sound, post it here, because it's probably the problem.