It's most likely the sound somehow got assigned to something other than the speakers, but there are numerous things that could have happened. Leo suggests a few things to try:
- Open the "mixer" in Windows' system tray
- Check the sound controls in Control Panel
- Check Device Manager for a working sound card
Right click on "My Computer", select "properties", and go to the "Device Manager" tab. Look and see if the sound card is working. It's possible that it was just a coincidence that it stopped working after Michael's nephew got ahold of it. It is a very old computer.
Look for the speaker icon, and right click on that to make sure the sound is turned up and not muted.
Michael says the sound controls were ghosted out here, and it wouldn't let him alter anything, but Leo says to keep looking to see if there's a way to choose the "speakers" as the device for audio.
The chat room suggests that it could be missing or corrupted drivers, but Leo thinks it most likely is that the sound is set to the wrong device.