How did you got rid of your complete menu bar at the usually top of the obs window?
Did you tried F11 to switch between fullscreen and windowed mode?
If you get at least the top line of the stats window back, you can pick the "stats" headline with your mouse and draw that dock into another part of your obs screen as you wish.
If nothing of that helps, you can try Alt-V (to get into the view menu on top and go into docks->reset).
