When for any reason, one of the margins of your window goes out of boundaries, specially when is the top margin, which is out of the boundaries of the screen.
Move or resize to put it inside boundaries again is not a easy task, in those cases, what you can do, is resize using the keyboard.
Just press ALT + F8 and the cursor will become a small cross, then you can move the mouse to the direction of the margin you want to resize. It will lock the margin and you can resize using the mouse.
Hope this small tip help you.