Not sure if anyone else has ever experienced this problem, but just in case I wanted to provide a link that somehow, someway might be found on the web to fix it. What you are probably doing is running dual monitors and switching between different screen sizes which can break the placement of the open window for Photoshop. To fix this you need to readjust your screen size setting of your monitor, this will recalculate the window placement for Photoshop and should put it back inside the upper boundaries of your screen size.

Basically got to: System Preferences >> Displays >> Temporarily change the screen size from “Default for Display” to scaled and pick a difference resolution >> Revert back to original default >> Now your photoshop window should be fixed.