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:

• The name of the library or university whose Ebook Central site you use, or the URL you use to access Ebook Central
• Your previous Ebook Central username (in most cases this will be your email address, if your library previously used the Ebook Central Patron Login authentication method to create accounts directly on Ebook Central)
• Your current Ebook Central username. The username seen by our system may differ from the username you use when signing in. To see what Ebook Central is using as your username, sign in to Ebook Central and go to Settings > Profile. Copy what you see under the "Email/Username" field
• Please allow several days for the bookshelf merge since we will need to schedule the work with the Ebooks engineering team

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.