To be honest, I dunno *what* I did that brought the 'puter back to life though I certainly didn't deliberately delete any dat files. While in Safe Mode with network capabilities (?) I tried restoring to 13August. No more distant date appeared available at the time. At first it wasn't successful. I tried it again and, well, it may have been what resuscitated the desktop.
Thanks Mele20
for hipping me to the connection between my recent dilemma and what was originally perceived as coincidence with the updates of 13August. It's a helluva note that what we've been led to believe and rely on from Microsoft turns out to be unhealthy for our systems.