What must I do to use the mouse wheel to Orbit? It has worked in the past, since Google.
Bill
Press down on the scroll wheel.
If that isn’t working there may be an issue with the mouse.
In addition what Box told:
The “Middle Mouse Button” should be assigned to the scroll wheel click. Usually you can check and change it with the setting software of the mouse.
What mouse you are using?
If your mouse behaviour changed without you changing any settings, first thing to try would be to shut down and restart your computer. If that doesn’t help, try a second mouse if you have one. Mouses also wear as time goes by, and for me, the mouse wheel button seems to have been always the first thing to break. CAD applications use it perhaps more intensely than it was designed for.