If a window happens to be off-screen, you can bring it back with keyboard shortcuts. First, make the app active (Alt + Tab). Then press Alt + Space, and in the drop-down menu that appears, select M (Move). Now use the arrow keys to bring the window back into view, and press Enter once you can see it. Besides that, you can press Windows + Shift + Arrow keys for snapping the window to whichever monitor or side. Another way is right-clicking the app on the taskbar, selecting Move, and using the arrow keys. Making screen resolution changes temporarily is also one of the ways to get a window repositioned.