Lightroom 6.14 update resets program to 6.0 and won't allow further updates

I've had LR 6.12 running solidly for months, and decided to update to 6.14 now that it's available.  Going through the Help/Update tabs I got what looked like a normal update process (had to close LR in the middle of it, as I've had to do in prior updates) but at the end it came up with a failure notice.  AND what is now on my computer is LR 6.0.  Clicking on Help/Update informs me that my app is fully up to date. 

I downloaded a new copy of LR 6.0 from the Adobe web site and it said it was fully up to date.  I then downloaded update 6.14 from the Adobe web site and ran it, which ended up with a failure notice and left me with 6.0 installed, saying it was up to date.  Same result downloading and running the 6.13 and 6.12 updates.

I called Adobe support and, after waiting 56 minutes for somebody to pick up, was told they don't talk to people about standalone products any more.  They gave me a link to the forums and said good luck.

So - does anybody have a suggestion for at least getting me back to a functioning version of 6.12? 

Thanks for any help.