What you do is take a screenshot of the desktop, rotate it 180° in MSPaint, set it as the background, hide and move the taskbar, hide desktop icons, and set the screen rotation to landscape flipped in the display settings. You'll get a desktop that appears normal but can't be interacted with, and a cursor that moves upside down and backwards. Rotate your victim's mouse the wrong way around if they're gullible and they'll think the mouse messed everything up,