Help

Go onto itunes on your computer and find the category "purchased" should be on the right side somewhere. Everything you purchased should be there to download for free, let me know if that works

http://support.apple.com/kb/HT2519

Here if purchased from iTunes.

Downloading past purchases from the App Store, iBookstore, and iTunes Store

If not you have to go to where you purchased them

I'm having this problem too! Did you ever find a solution?

neither of these work; the audiobooks don't appear.

That is because audio books do not allow a redownload. It appears that Apple has been unable to negotiate redownloads for audio book.

Worked that out. Rats. i'll contact iTunes, but will also try Audible, since they're Audible titles. and from now on, i'm purchasing direct from Audible. 8(