Using Free CAD 0.19.3 on Win-10.
I have lost "Combo View" window. Now all the windows are strange sized and position. Combo View is full screen or gone. I am in a unusable state. Tried reinstalling. I am about to uninstall and reinstall again. There is got to be a "back to normal view" button.
RonS.

normal view:

 

Mostly solved.
In the picture in post #1 there are three windows. If you, by ascend, bump a window it may fall off the screen or move to the middle or go full screen.
Fix: Move the window by mouse down on the top edge, hold the button down, move the mouse so it is at the left (or right) edge of the screen and in the center vertically. Center is important. Don't thin about where the window is but where the mouse is.