Sorry to ask such a basic question but Perspective View rotation by holding down right mouse key seems to have gone away. I looked into Viewport Properties and it is set for Perspective. I tried hunting for previous questions of this type but I am not the best finder of things.
As far as I can tell, there is no change to the Perspective View response to right click mouse movement after 4View twice. That is, it still does not rotate.
Without actually knowing that my first guesses are that there is some Windows “accessibility” feature–easy to turn on by accident–or other mouse mapping software messing up the right-click, or your mouse has physically died.
Restarting Windows did the trick. I’ve got Rotation back in Perspective – and learned a little in the process. My great thanks to William, Jim and Nathan – all was very instructive.