To play MP3 files in Windows Media Player, you need to make sure that you have checked "MP3 format sound" in the options. To make sure your Windows Media Player is configured properly follow these steps: 1. Start Windows Media Player 2. Go to "Tools" and then "Options" 3. Click on the "Formats" tab 4. Look through the list of "available file formats" 5. Make sure that "MP3 format sound" is checked 6. Click "OK" and then attempt to play the MP3 file again. If this does not solve your problem, try upgrading to a newer version of Windows Media Player. If this does not solve your problem, Go to the "Windows Media Player Download page" Read the "release notes" for the version of Windows Media Player that is installed on your machine. The release notes are detailed instructions for operating and troubleshooting Windows Media Player. For additional help with windows Media Player, You can also subscribe to the MSN newsgroup "microsoft.public.windowsmedia.player"