Currently Being ModeratedMar 27, 2011 9:17 AM (in response to HankGutstop)This happened to me, as well. I had to go into iTunes and reselect the books, then sync again.Mac OS X (10.6.6), iPad 1/2 WiFi 64GB - MBP 13" - MBA 11" - iMac 27" - Mac Mini
Currently Being ModeratedMar 27, 2011 10:47 AM (in response to HankGutstop)Same thing happened to me last night except ALL the books and PDFs disappeared. In addition, my Kindle app along with all the Kindle books I had disappeared.
Resolution was to resync.
No idea why this happened. Odd, though, it happened shortly after installing the Kindle app.
Food for thought.
Currently Being ModeratedJan 18, 2012 2:21 AM (in response to dlg_az)
All of the PDF documents on my iPad disappeared. This seems to be a problem that a number of people have experienced, although a clearly documented solution does not appear to be readily available.
This issue can be resolved by deleting all the PDF documents in the iTunes library. Copying the PDF documents back to the iTunes library and then syncing the iPad will allow the missing documents to reappear back in the collections into which they were filed.
It is a good idea to make sure that you have a complete backup of all of the PDF documents in the library before deleting them.
Currently Being ModeratedOct 31, 2012 11:53 AM (in response to HankGutstop)
The same thing happened to me when I upgraded my iPad and the OS. I eventually discovered that the sync checkbox in iTunes books section had been unchecked. Checking it resolved the problem.
Currently Being ModeratedMar 1, 2013 12:53 PM (in response to Raven45)
I was trying to make avoider of all iPad book stores a d kindle we t to a folder with kobo but when I attempted tpput it in with books and nook, already in a folder it disappeared! I can do a search and it shows up and my previously purchased books are in the amazon cloud, but where is the app? I read about not to do a recent update and didnt unless the iPad synced on its own?
Currently Being ModeratedOct 27, 2013 12:08 PM (in response to HankGutstop)
The same problem... iTunes show me 1,22GB of books but iBooks was reinstalled and no books in the newsstand either. Nearly 10% of storage for books isn't very funny.
Currently Being ModeratedOct 27, 2013 12:14 PM (in response to HankGutstop)
Now I got it... The solution is very simple. I re-install iBooks and delete the books at my iPad. The books are available in icloud right now. iTunes correctly displays 0GB of books.