A family of Microsoft word processing software products for creating web, email, and print documents.
As TaoLi suggested, a deactivated install could be the problem. In Word, click File > Account to find out if your Office suite is activated. Which info is provided there? Maybe you need to sign in with a different account—the account which is associated with your version of Office.
If activation is not the issue, try restarting your computer and then run an Office repair. See https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b .