Thank you. Good advice. However, since all system dll files were unreadable, I doubt that accessing system restore was possible (when I tried it...not in safe mode...but from a desktop icon whose path is directly to the System Restore application (rather than through control panel, which wasn't operable) it said that some .dll file was missing and the application could not be opened. BUT...it wouldn't have hurt to try. I made have gotten a pleasant surprise
Again, thank you. I'll remember this for "next" time (which I hope never arrives).