The Microsoft product support unit helped me to regain the lost function of
audio CD playback. Your situation may be different so take this for what
it's worth.  Please note that my system was always fully functional except
that neither WMP 9 nor RealOne ver. 2 nor W2K's CD Player would play audio
CDs.

My problem was caused by a random, unexplained loss of my
(MCI ) Audio CD driver and compounded by the erroneous 'Help' procedure in
the
Windows 2000 Hardware troubleshooter 'Help' file that did not properly
explain how to reinstall the driver. The following procedure helped me to
restore the lost driver and regain audio CD playback capability: Currently
my
RealOne application is the default player for my PC's CD audio
file type (.cda) and I'm sure that WPM 9 would do just as well if I were to
make it
the default CD player.

Please try the following steps to reinstall the MCI CD Audio
Driver: (NOTE: The hardware troubleshooter page in the Windows 2000 'Help'
files that instructs how to install the MCI CD Audio driver is erroneous.
The
following is the correct procedure)

1. Control Panel - Add/Remove Hardware
2. Click Next
3. Select "Add/Troubleshoot a device" and click Next
4. Select "Add a new device" and click Next
5. Select "No, I want to select the hardware from a list" and click Next
6. Select "Sound, video and game controllers" and click Next
7. Select "(standard system devices)" under "Manufacturers" and "Media
    Control Devices" under "Models." Click "Have Disk"

8. The "Install from Disk" window opens. Manually enter your PC's location
    for the System32 folder in the address window and click OK - (Example:
:\WINNT\System32)

NOTE: If you try using the 'browse' function with your mouse to enter the
address it may enter the wrong file. Key in the address manually!
9. Restart the computer and check if you can play an audio CD.

You might want to try checking Device Manager first to see if
the icon for the MCI driver is displayed. W2K displays the MCI CD Audio
driver icon under 'Sound, Video, and game controllers.'