Two ways.
1) Do the following to find out if that is indeed the case:
- Right-click on any image on the Windows 10 machine and select Open With > Choose another app.
- Select "More apps" if Windows Photo Viewer is not listed.
- Scroll down to see if the program is listed. If you see it there, Windows Photo Viewer is installed and ready for use.
2) Click here to download the PhotoViewer.reg file on to your Windows 10 PC.
- Double-click on the downloaded PhotoViewer.reg file and then click Yes button.
- Click OK button again.
That’s it! You have just enabled the classic Windows Photo Viewer in Windows 10.