Reset Mac OS X Windows Position after de-attaching external monitor

"From my answer originally at Server Fault Question 7237:

When a monitor is unplugged (including the adapter as well if applicable - leaving the adapter leaves OS X thinking the monitor is still plugged in) all the Windows should move onto your main screen. Occasionally some windows (eg. Firefox) will keep their position on the very far right of the screen leaving you just enough room to grab the title bar and move it where you'd like to.

One method of arranging the Windows so you can see them (if for some reason they're staying off screen) is to change to the application that owns the window in question, hold the Option key down and choose ""Arrange in Front"" from the Window menu. It will then arrange all the windows of that application in a cascade from the top left of the screen.

SEcondly, there are several AppleScripts available (eg. this one at Snipplr) that will also grab every window off screen and move it on screen for you.

There is also a nifty shareware app called Stay that will help automate a lot of this for you, while there is also ControlPlane which will do much more than just notice if a monitor is disconnected and allows you to run scripts (in case you want to do more than just rearrange the windows). ControlPlane is free, but doesn't have any direct mechanism for moving windows (you have to attach it to one of the aforementioned AppleScripts)."

breeze has global and application window states. the states can be triggered using they keyboard and are resolution independent. pair this with sizeup and windowflow and you'll be set.

"None of these worked, then I read about a trick to delete the plist file. That deleted everything including my registration for the app I was trying to gather the main window, which was open, when I last closed it.

Then I tried the following and succeeded:
I changed the key MainWindowFrame to s.th. below my screen resolution, in my case:

<key>MainWindowFrame</key>
<array>
<integer>**2237**</integer>
<integer>474</integer>
<integer>834</integer>
<integer>704</integer>
</array>

to:

<key>MainWindowFrame</key>
<array>
<integer>**1000**</integer>
<integer>474</integer>
<integer>834</integer>
<integer>704</integer>
</array>

That finally did the trick!!!"

I had a similar query for a friend that uses an external monitor with a Macbook, and he suggested SizeUp. I haven't looked into it yet, but it may be what you're after.

You can go to System Preferences > Displays and change the resolution to something lower, say 1024 x 768 or 800 x 600 and it will cause windows to reset to that smaller display size. Change it back to what you had an all off screen windows should appear.