Window is supposed to be a menu item.  If you are looking for the extra plugins that you have installed, like the career editor, I believe you will find them in Tools. (Possibly Extra... It's been a while.) If you are looking for the large window at the bottom labelled "Plugin view", I usually just use reset layout to get it back.  I -think- you can also get it back with an option in the Window menu, but as I said, I use reset layout.  (You should have the reset layout button on the button bar at the top of the screen. It looks like a blue and white circle with a red x at the bottom.)

Reset layout is really handy for any weirdness with the layout, although it puts everything back to the default placements so if you have added or removed buttons on the bar or moved windows on purpose you will need to do that all over again.