Open iTunes. Click "Edit" and select "Preferences." Click the "General" tab and select "Importing Settings" in the second row.
Select "WAV Encoder" from the "Import Using" drop down list and click "OK" to save the settings.
Highlight the MP3 track you wish to convert from your iTunes library -- if you wish to convert more than one song, hold down the CTRL button as you select each track. If the tracks are not already in the iTunes library, locate them on your computer, click and drag them into the library.
Click "Advanced" and select "Create WAV Version" -- the converted files can be found in the same location as the original.