My version of Audacity (which is old as fuck) sure does. Open your MP3 file with Audacity. Click "Ctrl+A" to select it. Then click on "File", "Export Selection As" or whatever it is in your language, and at the bottom of the window, you should be able to choose among different types of formats, including WAV. If it doesn't work, download the Lame MP3 plugin for Audacity and try again. It definitely works for me.