Situation:
In Word, Excel, PowerPoint and most other office applications the ribbon can be accidentally hidden.
Resolution:
At the top right corner of an existing or new document, you will find the following icon to control how the command ribbon is displayed.
Toggle the option as displayed below and it will always show up.
Make sure you close and reopen the document you have open so it will remember your selection.
It should now show your ribbon/menu bar: