When your library changes authentication methods, you may notice that your previously-saved items no longer appear on your bookshelf. With single sign-on authentication, you are signing in to your bookshelf when you log in to your library's system for access to the site. Because of this, a new account will be created based on the userID you use on your library's authentication system, and you will have a new bookshelf.
However, it is possible to retrieve items saved to your previous bookshelf. 

Submit a case to Ebook Support with the following information: If you're not sure what your previous username was, Ebook Support may still be able to identify your old bookshelf. It will help if you can remember some of the titles you had saved.