Did you "Create a Saved Book" when designing in the Book module?
Does it appear in the Collections panel of your catalog?
Did you need to update your catalog when you did the LR update?
Please check are opening the correct catalog file in Lightroom.
Go to file menu >> Open Recent and open all the recent catalogs and see if you can find your Book.
Let us know if that helps.
I dont know what happened but my book came back. IT never showed up under my collections last night and now it is.
Great, Nice to hear that.