Many users have reported losing commands from their menu bar. Try these
fixes (in order):
1. Open the Customize dialog using one of the several ways other than Tools
| Customize (my favorite is to double-click on the empty area of any
toolbar, but you can also right-click on a toolbar and choose Customize). On
the Toolbars tab, select Menu Bar and press Reset.
2. If that doesn't work, switch to the Commands tab and select Built-in
Menus in the Categories list. In the Commands list, select the Tools menu
and drag it to the menu bar.