SOUND ERROR

I CANNOT GET SOUND ON MY COMPUTER FOR I BELIVE I CHANGED
MY DRIVER BY ACCIDENT THE ERROR MESSAGE I GET IS AS
FOLLOWS: AND COULD YOU PLEASE TELL ME HOW I COULD FIX THE
PROBLEM, THANKS!


PRO0xC00D11BA: Cannot play the file
Windows Media Player cannot play the file because there is
a problem with your sound device, such as a sound card or
sound controller. You may encounter this error message for
one of the following reasons:

Your sound device is in use by another program. Quit other
programs that may be using your sound device, and then try
to play the file again.
Your sound device is not functioning properly. To
troubleshoot the problem, see the Sound Troubleshooter in
Windows Help or refer to your sound device's
documentation.
You do not have a sound device installed on your computer.
Install a sound device, and then try to play the file
again.
Error ID = 0xC00D11BA, Condition ID = 0x00000000