When you have multiple monitors and then move from site to site with different monitor configurations not all software correctly handles its locations settings. When a windows knows it's last location does not exist it should then display itself in the default position on theprimary monitor. When these setting are not updated you can not see the windows to move it to a live monitor, and thats the problem. There are solutions to this.
Simple Method
Not all software supports this so if this does not work use command now.
My example cmdow batch file
This will restore the UltraFileSearch window when it is off screen to the top left of your primary monitor.
cmdow "ultrafilesearch lite" /mov 0 0 or cmdow "UltraFileSearch Lite" /MOV 0 0 or cmdow 0x00A157E /MOV 0 0 ------------ window Window to list. If not specified all windows are listed. Specify a window by its unique handle in hexadecimal format (0x1A0142) or its caption (case insensitive). Wildcards may be used. Windows without captions may be specified by their ClassName. The At symbol '@', may be used to refer to this window ie 'CMDOW @'. Use double quotes for captions containing whitespace or control characters.
Notes

www.autohotkey.com/docs/commands/WinMove.htm
AutoHotkey - a scripting language for desktop automation and is an open source software. It is completely free for personal and commercial use.
The WinMove command Changes the position and/or size of the specified window.

Cmdow is a Win32 commandline utility for NT4/2000/XP/2003/2008/7 that allows windows to be listed, moved, resized, renamed, hidden/unhidden, disabled/enabled, minimized, maximized, restored, activated/inactivated, closed, killed and more.
It is ...

superuser.com/questions/676675/how-to-reset-the-window-posit...
Applications that store and restore their absolute window-position, might end up outside the visible screen if the monitor's screen-space changes. This happens for instance when de/attaching an external monitor.

darrenmyher.com/2011/12/22/moving-windows-from-non-existing-...
If you have a notebook computer connected to multiple displays at home or work then disconnect that display, you can sometimes end up with windows that when restored show on the now non-existent 2nd display.

www.sevenforums.com/tutorials/75291-offscreen-window-move-ba...
If you have a opened window that is offscreen from your main display, then this will show you how to move the offscreen window back on your desktop in Windows 7 and Windows 8...

stackoverflow.com/questions/7977322/set-the-window-position-...
I have an application which start in 0x0 position of my desktop. I want to open it in center of my desktop. I do not want to open it and use a move command to move it into center, just want my app to start immediately in center position.
Is the ...