Short answer? I didn’t take it down, so I’m not sure.
Some possibilities are that it got caught up in the latest “porn sweep” (Forbidden Love and Stripped Clean were briefly taken down from Kobo Books, and Stripped Clean has been returned to their catalog but Forbidden Love has not last I checked) or it could have been a random glitch. Unfortunately I didn’t realize Yes, Sir had disappeared from B&N until a reader complained by way of posting the fact that Yes, Sir had been taken down in a Goodreads review, and while I try to check on these things periodically I do tend to assume my books are where they’re supposed to be unless I’ve done something to change their status.
At any rate, I’m looking into finding a solution for the problem and determining the best possible fix. In the meantime, if you want Yes, Sir in .epub format specifically, it is still available at Kobo Books, and All Romance Ebooks.
If there is any further issue with the availability of this or any other of my books, please do email me to let me know (ellis carrington at gmail). It’s the easiest way to ensure I can be responsive to my readers, and I do want my readers to be happy. 🙂