All my books have disappeared
All of my books and PDFs have disappeared from my iPad (3). I thought they were being backed up by the iCloud. I don't think I changed anything recently.
Suggestions would be appreciated.
2.7 GHz Intel Core I5, 27� iMac
12 GB Ram, 1TB HD, OS 10.7.4
iPad (3), 32 GB, iOS 5.1.1