Linary wrote:
It is possible that th3e Lock File is still present.
Close Lightroom (or cease any attempts to open it), and search you computer for a file "Lightroom Catalog.lrcat.Lock"
If you find such a file (on my computer it is located in my Lightroom folder where the catalog and Smart Previews are located), delete the file, reboot the computer and try to open Lightroom.
Thanks, Linary. We'll try this before going to the Microsoft store. He's changed focus (after way too much frustration on Easter Sunday!) and is finishing up our taxes.