Thank you for your question and reaching out. I can understand you are having query\issues related to .png can not open.
- Please try to reset or Repair Photos app.
Click on Apps and select Apps & feature from the left pane.
Scroll down and select Photos App on the right pane.
Click on Advanced option and then click on Reset or Repair.
Restart the PC and check.
- Please try to Uninstall and reinstall Photos App.
Get-AppxPackage Microsoft.Windows.Photos | Remove-AppxPackage
Then Open Microsoft Store and install the Photos app.
- Run sfc /scannow from elevated prompt.
- Run below DISM commands from elevated prompt.
DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
--If the reply is helpful, please Upvote and Accept as answer--