Audio books disappeared with update. Help?

I have an iPhone 4s, which I just updated to iOS 7 and synced to my Macbook, on which I also just updated the software/OS. Before these updates, I purchased several audiobooks on my phone and could easily access them through my phone's iTunes. However, now that I have updated to iOS 7, all of my audio books have disappeared completely. All the music I purchased is still there and available, but not a single audio book is there. Am I just missing something??? It's as if they never existed, but I still have the receipts. Does anyone know how to access previously purchased audio books on iOS 7? This is amazingly frustrating, so any help is appreciated! Thanks!