Hi, I am an independent advisor, and welcome to Microsoft Q&A. Let me help you with this issue.
Have you tried a quick repair?
Click on the Start Menu, type in Control Panel, go to Programs and features, and go to Uninstall a Program, scroll down to Microsoft Office, right clic,k and choose Change, click on Quick Repair.
Once done, see if Excel works. If not, perform the same steps, and this time, choose Online Repair.
The Online Repair will uninstall and reinstall the Microsoft Office suite on your machine. This will require an internet connection and may take some time to finish.