My PDFs have vanished from ibooks
pdfs I have had for ages in iBooks are all gone... All their folders are blank
OS X Mavericks (10.9), iPad2, AppleTV v2, iphones, macbook
What have you done since you last had them on your iPad e.g. updated the iOS version on it, synced to your computer's iTunes with the PDFs not in the computer's iTunes/iBooks library ? Do you have copies of them on your computer so that you can sync them back to your iPad ?