If an Office application such as Word or Excel isn’t working correctly, sometimes restarting it will fix the problem. If that doesn’t work, you can try repairing it. When you’re done, you might need to restart your computer.
Repair Office from the Control Panel
The steps to access the repair tool vary depending on your operating system.
Windows 10
Choose your operating system from the tabs below:
Right-click the Start button 
(lower-left corner), and select Programs and Features on the pop-up menu.
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.
Note: If your copy of Office is MSI-based, select Repair and then click Continue. If you need help figuring out if your Office is Click-to-Run or MSI-based, follow these steps below.
Follow the instructions on the screen to complete.
Windows 8 & 8.1
Right-click the Start button (lower-left corner), and select Control Panel from the pop-up menu.
From Category view, under Programs, select Uninstall a program.
Right-click the Microsoft Office product you want to repair, and select the Change button.
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 make sure everything gets fixed, and then select Repair.
Note: If your copy of Office is MSI-based, select Repair and then click Continue. If you need help figuring out if your Office is Click-to-Run or MSI-based, follow these steps below.
Follow the instructions on the screen to complete.
Windows 7 & Vista
Click the Start button 
> Control Panel > Programs and Features.
From Category view, under Programs, select Uninstall a program.
Click the Office product you want to repair, and then click Change.
Follow the steps for your Office installation type:
Click-to-Run: From the How would you like to repair your Office Programs screen, select Online Repair to ensure everything gets fixed, and then select Repair.
MSI-based: Select Repair and then click Continue.
Follow the instructions on the screen to complete.
Is my Office installation Click-to-Run or MSI-based?
Open an Office application, such as Outlook or Word.Go to File > Account or Office Account.
If you see an "Update Options" item, you have a Click-to-Run installation. If you don't see the "Update Options" item, you have an MSI-based install.
Running Repair didn't help. Now what?
If running Repair doesn't solve the problem, you might need to uninstall and reinstall Office. See Uninstall Office 2010 or Uninstall Office 2013, Office 2016, or Office 365 from a PC.
**Office 2013, 2016, and Office 365 will potentially ask for a product key or email address that is associated with the product, make sure that this information is handy.