Navigate to a single mp3 file on your computer. If you're using Windows XP, RIGHT click on the file (or hold down the "shift" key and right click), choose "Open With" from the menu, then select "Choose Program". When the "open with" menu opens, place a CHECK mark in the "Always use this program to open this file type", then double click on the "Windows Media Player" listing in the upper window.
The file should immediately play using WMP and it should become the default player for mp3.
Hope this helps.
I have a Dell XPS 400 which came with Music Match and Windows Media Player and for MP3's, Music Match is the default player. How can I change it to default to the WMP?