Log in to an administrator account. You must be logged in with administrator privileges to change file permissions.
Click "Start" and then "Computer." Navigate to the folder containing the locked MP3.
Right-click on the locked MP3 and select "Properties." Click the "Security" tab and then click "Advanced."
Click the "Owner" tab. Click the "Edit" button.
Click on your username in the box labeled "Change owner to." Click "OK"; if a warning box pops up, click its "OK" button. Click "OK," then "OK" again.
Double-click the MP3 to play it in Windows Media Player or another media program that you have associated with the MP3 format.