Any or all of the following settings can be knocked out by viruses etc.

... You may already have tried this:

1. Double check that the sound is not muted:
start>All Programs>accessories>entertainment>volume control

2. Check under control panel>system>hardware>device manager>sound video and game controllers You should see an entry something like 'Soundblaster' or 'AC97'. This shows the hardware is installed OK. If there is a big yellow exclamation mark you will need to reinstall drivers.

3. control panel>sound and audio devices ...
double check that the device in(1) above matches the default device in the audio tab.

4. (phew!)
Check Media Player:
tools>options>devices>speakers ditto to (3)

Its worth sticking heaphones in the socket as well just in case your speakers are kaput ...

AP