How come my valid library card and pin keep coming back as invalid?
Nooks don't come with explanations on how to download from libraries, do they?!
It looks like we may have two separate issues here.
First, your library account does expire after two years and it has been renewed. The card number you provided is the number you need. The pin number will be the 4 digit number you chose as a PIN number. There is now also a "Forget a PIN" feature on the library's website if you suspect this number is the cause of the problem.
Secondly, a Nook can't download books directly from the library's website. Books need to be downloaded first to software called Adobe Digital Editions on a Windows or Mac Computer and then transferred to your eReader (either ePub or PDF format will work with a Nook). See How to Download an Ebook and examine your system requirements and download Adobe Digital Editions . You will also be prompted for an Adobe ID, which you can easily create . After you have successfully set-up ADE on the computer, leave it open, attach the Nook with its cable, and you should be prompted to authenticate with Adobe ID. After that you will be able to download books from the library's website (they will appear in ADE) and then drag-and-drop them onto the Nook icon in order to make the transfer to the Nook.
I hope this helps! Good luck and enjoy!