Windows 7 allow users change the program associated with file type using the default program settings available as part of Control Panel. You can use the same “default program” settings in Windows 8 as well. For example, Windows 8 by default plays all .mp3 files in the new Music App but if you want to use Windows Media Player then navigate to Windows 8 search screen and type default programs in Search text field.
Clicking the Default Program available on the Apps Result page would display the Default Programs settings window.
Now click the Associate a file type or protocol with a program. In the Set Associations window, select .mp3 file extension and click the Change program button.
Select Windows Media Player from the list of available programs for .mp3 file type.