Over the last year, it seems that more and more often in Psychopy the window has somehow gone offscreen. Sometimes this happens when one has an external screen connected and disconnects it. When it’s only partially offscreen, holding the option key when resizing any available corner can help get it fully onscreen. https://www.tekrevue.com/tip/use-the-option-key-to-quickly-resize-windows-in-os-x/
When it’s entirely offscreen, if I remember correctly one solution is to delete a Psychopy file in the Library/Preferences folder. Maybe someone knows details and wants to chime in.