Well, I might be writing this article late, but as said better late then never. Windows 10 comes up modern app known as Photos and is a replacement for Windows photo viewer present from ages in Windows.

A comparison of Windows photo viewer and photos app

Though photos app provides far more feature than the traditional photo viewer like Editing,sharing a photo etc. Still many people like me prefer Windows photo viewer over Photos app. Sometimes the photos app take ages to load a tiny photo, sometimes the app is broken and doesn’t even open etc. etc.
So to overcome this, restoring Windows photo viewer is a good idea.
Windows photo viewer still exists in Windows 10 but is limited to open only TIFF files(which are very common :)). With the help of  a registry edit, we can restore windows photo viewer for common extensions like JPG, GIF etc etc.

Download

Download the registry edit to restore Windows photo viewer

Open the downloaded file, press yes when prompted.
Afterwards, you would be asked “How to open this kind of file??”
Select Windows photo viewer once and you are done!

Undo changes

Registry script to Restore photos app as default