Update: This glitch has been fixed for Favorites from Amelia’s Kitchen, and presumably has been fixed or soon will be fixed for the other books that were affected.
There has been a glitch with many books in Amazon’s KDP program that has them “vanished” from the online stores. They still show as “live” and on sale in the author accounts, but they are not to be found in any of the sites (.com, .uk., .de, etc.). They are apparently working to correct the error, and hopefully it will be completely fixed within the next day or two. So if you’re looking for a book that you know should be available on Amazon, such as Favorites from Amelia’s Kitchen, but you get a 404 Not Found error, it may very well be that it’s a victim of this glitch. Just try again tomorrow or the next day.