If your catalog is still intact but the list of keywords has disappeared, then if you'd like to send us a copy of your database (the file that ends in .pmdb in the location where your catalog is stored) then we can run a query on your database and export them to a file for you and send that back to you. For a future version of Photo Mechanic, we think it would be a worthwhile improvement for Photo Mechanic to provide a way to export all of the keywords in a catalog to a file, which you could import into your keywords list.
With that being said, I took a look back at your previous posts, and I have to wonder why this issue keeps happening, because I noticed that you made a post from about 2 years ago where the same thing happened, and another time where you mentioned that it is continually losing your catalogs. I'm not aware of issues like this occurring this regularly for other users, so I have to wonder why you've had multiple occurrences of files that are important to your use of Photo Mechanic being lost. I'm not even really sure to begin with the problem, but if you want to give our support line a call, maybe we can figure something out.
If it is of any help at this point, the last time you needed to recover your keywords due to an OS downgrade, you apparently had a backup where that allowed you to recover them, so maybe that will be simpler than having to send us your database:
https://forums.camerabits.com/index.php?topic=16037.msg78349#msg78349