We've had a couple of library books that we couldn't find anywhere. One was mine, and one was N's. I knew the last place I had seen mine was on my dresser, but that was a few weeks ago. And I had no idea where the last place I had seen N's book. I spent several weeks looking everywhere those books could possibly be, again and again. Then I started looking in all the places the books couldn't possibly be. Unfortunately, there are a lot more of those. But they were still nowhere to be found.
Finally, after all the times going into the library, and having the librarians keep on reminding us that those books were still out, I did something. Out of curiosity more than anything else, I looked on the shelves where my book would be. I found the book there, and took it up to be scanned. Sure enough, it wasn't just a copy of the book; it was the same one I had taken out. So then I went to the kids section of the library, found N's book, and guess what? It was the same book. I should have had them check on it a month ago.
Now if I could only find my library card.