I have no audio on one episode of a show that I have downloaded on itunes.
I have no audio on just one episode of a show that I download from itunes. All other episodes are fine.
Windows 7
I'd report the problem to the iTunes Store.
Log in to the Store. Click on "Account" in your Quick Links. When you're in your Account information screen, go down to Purchase History and click "See all".
Find the item that is not playing properly. If you can't see "Report a Problem" next to the item, click the "Report a problem" button. Now click the "Report a Problem" link next to the item.