1. Ask the ed teacher to give you another copy. It's hardly imaginable that the copy on the USB stick is his only one.
2. If you can open the documents OK with Wordpad, isn't that enough to deal with them? What exactly, by the way, are you supposed to do with the documents?
3. Try it on another machine (unlikely to help, of course).
4. Are you sure it isn't a font problem? Characters in unknown fonts might be unreadable. What happens if you select all and change the font to Arial, for example?

It's far from sure that commercial repair software will help, of course. Better try the free demo mode first, if it has such.

And, remember, it's not your responsibility to manage his documents. If they are corrupted on his computer already it's his responsibility. All you can do: try repair software, without any guarantee of success.