Windows Photo Viewer is the default photo viewer app built-in since Windows XP and it offer various options like printing, attaching, edit (via Paint), and burning. But in Windows 10 it no longer used as default, replaced by Metro UI Photos app which has limited features and sometimes unresponsive, and it no longer showed at "Open With..." menu.
Some user prefer using Windows Photo Viewer which is missing in "Open With..." context. This is the steps to show it again.
IMPORTANT NOTE: You must logged in as Administrator to execute this
1. Download this registry file
2. Double click the "photoviewer_activator.reg" files
3. Press "Yes" when you asked for UAC Permission.
4. Press "Yes" when that question showed.
5. Press "OK", then restart your PC.
6. It'll showed in "Open With..." context menu.