Mac monitor is displaying screen but I cannot navigate my cursor to it
Check that the virtual display arrangement in System Prefs > Display > Arrangement is the same as their physical placement.
You can only move your mouse across between the two at the side where they join.



You can drag &amp; drop either of the virtual screens until they match your physical layout. When dragging, both the virtual &amp; real screen will display a bright red border, so you know which you are working with.
The white menu bar can be dragged separately &amp; should be placed [if it isn't already] on your main monitor.

Also note that if the screens are not the same resolution [size actually doesn't matter, only resolution, as displayed in that control panel] then you may have a smaller 'gap' where you can pass from one to the other, as in this picture...