1. Check your speakers. Plug the audio cable into a standalone MP3 player. Is there sound?
2. Check your sound output. Get a pair of headphones. Plug the headphones where the sound output goes. Any sound? You did plug the speakers into the correct port didn't you - not the line-in by mistake?
3. Check your device settings. Is the sound card device driver correctly installed? I am quite sure this won't be the problem unless you have a discrete sound card, as moving the machine won't cause this.