So I downloaded the latest Windows10.iso, from MS, mounted the image then ran setup. I followed the process for "updating" the operating system (as a repair install) and selected "Keep personal files and apps".
Nervous 20 minutes or so while it ran through the "update" but once done, everything was still there and working (except for Strike Fighters 2 obviously.... )
On the point of giving up when I tried closing some small apps that are running the background. When I closed a program called Simply Sticky Notes (this is not the Sticky Notes app included with WIndows 10 but a freeware program), SF2 decided it would run! I don't know why this program would not allow SF2 to stay open. Hope it will still run again tomorrow.
Time to download and install some mods!
A big thank you to MigBuster for the advice and suggestions!