No books appear in library

Win 10 Pro - ADE ver 4.5.11.187212 ---- I can download books from the local library, but they do not appear in the "Library" of ADE. I attempt to "Add files to Library" and get a message that they are already added. When I try to open the downloaded book, it won't open... nothing happens. By this time, ADE has frozen and I can only close it using Task Manager.