Did you someone manage to lose the file menu in your Firefox and can’t seem to get it back? 

I came across this problem and knew there had to be a quick fix for this. After right clicking everywhere I was unable to get the file menu to reappear. I found that all you have to do is hit the “alt” key.

This will make the file menu reappear and then to make sure it stays in place click on View then select Toolbars and click on Menu Bar. This will put a checkmark next. Here is where you can also uncheck other toolbars that you may no longer want to show up.