If you go to Settings->Backup and Restore->Restore Automatic Database Backup, you can recover your library/database, but the problem is that all the PDFs and such were most likely deleted. So you'd have to copy all of the PDFs back into the storage location, then to go Settings->Other Settings->Fix Broken File Paths to link up the database to the PDFs. You can see how many files are missing under Settings->Other Settings->Find Missing Files.
Mike
Mike