Jim, appreciate the reply. What I did after this happened was go to my most recent back up which was five days earlier, and I launched that. I then re-imported the files that had been imported post back up, some of which had been edited. As I'd replied to dj paige, the edits I'd done post-back up were there on the re-imported images, however unfortunately the history on them has been wiped out - or at least it no longer shows up in the catalog. But If I'm understanding you, I should have been able to locate the catalog as it was just before the update? Because I did not see a catalog more recent than what was in the back up folder and dated Sept 1st. Obviously I don't have a clear understanding of how this all works, so will have to do some studying up.
Thanks again.