Dual screen to single screen forgetfulness

[enonod]

I move an app window to the second monitor while using another on the MBP screen.
I close the moved app at some point without thinking ahead.
A few days later I take the MBP somewhere and run the first mentioned app, which now does not appear on the single screen. It is of course on the disconnected second monitor.
I have been unable to find a way (other than always move items back before closing) of returning the missing window whilst using the single screen.
There must surely be a way to do this (other than returning home to move the item).
Can anybody help please?

 

[Cory Cooper]

Hello,

Have you tried changing the settings in  > System Preferences... > Mission Control...specifically Displays have separate Spaces?

C

 

[enonod]

Thank you for your time Cory. I did not know about that setting but upon checking it I find it is set anyway. Most windows return to the main screen

I cannot remember what the application was and am doomed to await a repeat circumstance.
I have since discovered that another window is notorious for bad behaviour if its settings are not done well; Inkscape under X11; and even then frequently disappears or its dialogs are off screen, but that is down to 'earlier' programming and bugs.

How odd, I have just reread your answer and realise you said 'change' as opposed to set.
I will take more note in future and return for a solution if it reoccurs.