Time Turner only wanted to cure baldness.
The Doctor wanted to find a way home.
The two know must live in each other's (horse) shoes, trying to find a way back to their world. But first, Some Thing Wants Them To Learn Something. And It won't let them return until they learn it.
Too bad neither of them have any clue what they need to learn.
Why would he want to do that? Baldness seems very rare in the show.
10320034
True. But I wanted him doing something simple.