I discovered today that I had lost ALL OF the pathnames from my PATH system variable - all, that is, except for the Simply Fortran path, which, in my case, is
C:\Program Files (x86)\Fortran\Simply\mingw\bin.
This is all that there was in my PATH variable.
This is not too much of a disaster, I think, because I have been able to type back in the most obvious pathnames and I daresay I'll find out one way or another is there were any less obvious ones I also need.
I've searched my various startup tricks with virtual drives to see if this is anything I've caused myself, and I don't think it is. I therefore don't know how this has happened, but I am just wondering whether there is any possibility of an accidental error in the Simply Fortran 'install' process. Perhaps the Simply Fortran installer replaces the path variable contents with its own pathname rather than extending the existing contents of the system path variable by appending its own pathname to the end.
Most probably there is no such error in the SF install process but I thought I should ask - just to eliminate this.