Originally Posted by Starson17
If you're hand editing, it sounds like you want to do more than just repoint the old entries. You may find the following search to be useful:
It will show you all records that don't have any actual books in them. That's how I'd make sure that I missed no records if I was doing it automatically. I assume that you had at least one book format in each record before you had your problem.
I was doing the same thing by sorting on file size. The entries with no books attached have no file size.
The problem is that the whole calibre folder is wonky with some books missing. I have a backup folder with those books but it is missing other books, so have to switch between the two. Plus I need to make sure the right record is the dominant one in the merge process. One of the most important items I need to keep is the date. I use it to keep track of my reading. The re-added files often add with today's date and I don't want to lose the old date.