A family of Microsoft word processing software products for creating web, email, and print documents.
1
Right click a Word document and select Properties.
On the resulting dialog, click the Change button.
In the resulting list of apps, select a different app to open Word documents and apply that.
Then, repeat the process and set Word as the default to open .docx files and apply that.
2
If that does not resolve the problem, open the Settings App, and go to Apps - Installed apps, is there any other version of Office installed on your PC?
If there is another version of Office installed, uninstall it and restart your PC.
If there is no other version of Office installed, the best option is to perform a full repair of your Office installation.
Open the Settings App (gear icon on your Start Menu)
Go to Apps, then scroll down to find Microsoft Office
Select that and choose Modify - Online Repair
That should fix any issues with your Office Installation.