OK, I'll take it more seriously. Sorry, I thought it was the computer equivalent of a 'bad hair day' but I've recreated the same thing and see what you mean. For me, I just click on another file in the shelf and then the green button brings it back up. Then if I go back to the original problem folder the window behaves itself.
there's a program called "megazoomer" or similar to that, which allows you to make the most front window to fill the screen when you press Cmd+Enter.
so, install it, and press Cmd+Enter. hopefully it'll make that 10-mile window to shrink back to full screen, and then you can manually resize it using its corner