error message that says my Ipad is synced to another library

I get an error message when I try to look at the books and PDF documents on my Ipad that states the Ipad is synced to another library. I have had the same login for about 5 or 6 years. The only check is on my computer. I have to use a different log in because Norton screwed up my other log in but they moved all my files, etc. to the new log in. How do I fix this problem?

thanks