Sound

We need more details:
What version of Windows,
Sound card, or on-board sound?
If on-board sound, model of the motherboard.
What other plug-in cards are installed?
What have you tried downloading and installing?

You can use a utility such as Belarc Advisor www.belarc.com to get the details of your system configuration.

In the meantime, look in device manager.
(Right click on My Computer, and select properties.)
Are there any yellow "?" or "!" ? These are used to highlight devices that have hardware conflicts, or driver issues.

Chas

The fact that you say your CDROM plays back lets you know the sound card is functioning but something has the rest of the sound either turned off or disabled.

Go to control panel, select the sounds and multimedia icon. Click the Audio tab and see if there's a device selected for playback, this should be your sound card. You can click the volume botton and see if the wave volume is turned down or muted. Also click the advanced button and make sure desktop speakers is selected.

The other issue may be that you don't have the multimedia coponents completely installed. Again open control panel and select add remove programs. Choose windows setup from the top tabs. Go to the multi-media icon and double click that and select everything by making sure there's a check mark in front of the choices. Click OK then let that run and reboot when asked.

It would help to have more info on your system.

Good Luck