1
Open the Settings App.
Go to Apps - Installed Apps.
Scroll down to find the Microsoft Photos app.
Select that app, click the 3 dots beside it and choose 'Advanced Options'.
Perform the Repair option and the Reset option on the app.
Then check if the photos app is working correctly.
2
If that does not resolve the problem, uninstall the photos app, restart your PC, then download and install the latest version of the Photos app from the Microsoft Store.