Click on the "Control Panel" button on your computer. Then go to "Folder Options." On that screen, select "File Types." This generates a list of all of the extensions that your machine can read.
In the list for 'Registered File Types," scroll down to the WAV extension and view which program has been already associated with opening the file.
On that screen, click the "Change" button. This will allow you to specify which program automatically plays the WAV upon opening. Change the associated program to Windows Media Player. The next time you open any WAV file on your machine Windows Media Player will automatically open and play the WAV file.