I have an external monitor I use with my MacBook Pro. The MBP is the secondary monitor in this system. Somehow, when I unplug the external display, it isn’t resetting to make the MPB the primary monitor again, and I can find any setting or keyboard shortcut to make it detect displays. Help!
— Todd Peperkorn
That's odd. I don't know of any solution. Perhaps try launching display prefs before unplugging, so you have the "Detect Displays" button available. Make sure that is on your MBP monitor before you unplug. Then press that button after you unplug.