right click start menu
select control panel
from Category view, under Programs, select Uninstall a program.
Right-click the Microsoft Office product you want to repair, and select Change.
NOTE: If you have a suite such as Office 365 Home or Office Home and Student 2013 or 2016, search for the suite name, even if it's just a particular application you want to repair such as Word or Excel. If you have a standalone application such as Word or Excel, search for the application name.
From the How would you like to repair your Office Programs screen, select Online Repair to ensure everything gets fixed, and then select Repair. You can select Quick Repair which runs faster but only detects and then replaces corrupted files. Online Repair does an uninstall and complete repair but takes longer.
Follow the instructions on the screen to complete.