Update Won't Roll Back

Patch Tuesday was 2 days ago. This morning, when I rebooted, something had trashed my desktop, 2 email programs, Word, most of my startups, etc. I assume this was Windows Update but can't be sure. Win is now Version 1903 (Build 18362.1082); was 1903 but I don't know what build.

When I tried to roll back to yesterday's version, it told me this was "no longer available because your PC was updated more than 10 days ago." (That's what makes me wonder if my problem really is an update.)

Any suggestions?

Total misdiagnosis on my part.

Had accidentally rebooted into the Administrator account, which I had not used in about a year, so that identity had no idea of what I'd been doing lately--and little idea what I'd been doing before that.

Newmaven said:

Total misdiagnosis on my part. Had accidentally rebooted into the Administrator account....

That's a relief...

Newmaven said:

...When I tried to roll back to yesterday's version, it told me this was "no longer available because your PC was updated more than 10 days ago."
(That's what makes me wonder if my problem really is an update.)

That's also a misdiagnosis. The 'Go back to the previous version of Windows' option that you looked at is not for uninstalling cumulative updates, it's for rolling back after a version upgrade, such as when you upgraded 1809 to your current 1903.