If you are using later versions of ubuntu and the menus at the top of your windows disappear, first check to make sure they aren’t just at the top of the screen since that is the default position for them instead of within the application window. Very stupid, but that can be change, but sometimes they disappear altogether. How do you get them back? Run this command in the terminal.
initctl restart unity-panel-service
There you go. You’ll probably have to run it everytime you reboot so a script you run after you reenter ubuntu would be best. This is a bug of some sort that they are supposedly working on. It never stops amazing me how the fundamental aspects of an operative system like menus can be neglected so badly but the development teams.