Are you able to open the Word and PowerPoint apps by double clicking the app's icon without opening a file or are you also seeing an error then?
If so, the solution depends on the error you are seeing.
1
If you are seeing a popup error dialog with a 'Repair Now' button:
The 'Repair Now' button on that error popup dialog only performs a quick repair of the Office apps and that rarely resolves the problem with the Office apps, the best option is to perform a full online repair of your Office installation.
Before performing this process, please log into your Microsoft account on this link (https://account.microsoft.com/services/) and check to ensure your Office licence or Microsoft 365 subscription is listed correctly on your account.
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.
2
If that is not the error you are seeing, please provide a screenshot of the error indicated in the Office apps.