Dual-monitors, window hidden

Switching from dual monitors to a single monitor then losing windows?

Select ALT-SPACEBAR on your keyboard, then 'M' (for Move), then use the keyboard arrow keys to move the window back into view.

I have used this trick for a few years and it works great!

Before I switch from dual to single monitors, I drag all of my windows to my primary monitor before closing them. This will save the positions for the next time they are open.