I have an iphone 6+. ios 8.1.1. This am I was looking at my PDF files in ibooks and there were no issues. This afternoon (after no changes, updates or anything other than normal phone use) all my pdfs are gone. These pdfs were files which I had downloaded from the internet in the past and not purchased via itunes. When I arrived home, I synced my phone with the mac desktop thinking their might be a slight chance this might help, but no help. Thanks for any insight.