I just downloaded 2.0.5. I imported a song from my iTunes library, changed the tempo and tried to play it back…nothing. Play button moves but no sound and the line over the audio graph doesn’t move. I exited without saving, re-imported the song and didn’t make any changes to it, just tried to play it. Still nothing. Such a basic thing I’m trying to do and can’t make it work.
Install or reinstall the Audacity 2.0.5 exe from here: http://audacityteam.org/download/windows , making sure you put a tick (checkmark) in the “Reset Preferences” box half way through the installation process.