Missing bookshelves?

When I open ADE,there are no bookshelves under the 'Bookshelves' tab, not even the default ones. When I try to drag and drop any ebooks into ADE, I get a prompt saying that the ebook is already in the library but there is no way I can see my library anywhere in ADE. Also, when I try to add a bookshelf, it does not appear and nothing happens.