The problem was that the latest Nook update won't work with Adobe unless you have an ID and a password. In the olden days--before yesterday--I got my library books through Adobe and then transferred them to my Nook. Simple. Easy. Even I could do it. But then I left my wireless on too long and the Nook updated. (I don't use the wireless unless I'm buying from B&N, as the wireless uses a lot of battery power.) Then it wouldn't let me get library books. I had error messages. There were no books.
I wept. I screamed. I tore my hair. I called to J. "Fix it," I said, "or I'll never be able to get another book from the library and I'll have to buy them." J set to work. He took my computer, he took my Nook, and then magic happened and I was restored to ebook borrowing. Unlike many people, I did not have to restore my entire library, or re-set everything on the Nook.
But I'm still irritated that Nook didn't solve this problem months ago.