No sound from PC speaker system

Turned on my PC a few days ago and my Creative speaker system was dead. Does anyone have any idea what's wrong and how to solve this problem?

I've plugged my earphones into the sound card and can get sound that way, so at least the sound card is OK.

I've tried connecting the AC adapter to a the speaker system of a second computer, and the subwoofer started humming while being off. Using the AC adapter from the second computer had no effect on my Creative system.

Sounds like a wire loose inside the speaker/sub woofer.... try shaking it a bit (not joking)... if not it may require opening to check for loose wires...