Samsung SM-J110G how do I transfer photos from Photos to Gallery

[AC Question]

Somehow my pictures in Gallery ended up in Photos. I want to transfer them back to Gallery.

 

[Rukbat]

You don't - they're not "in" either Gallery or Photos, they're either in the phone or in the cloud. The media scanner scans the entire phone when you turn it on, finds all media files and builds a database of them. Both Gallery and Photos look there to see what to display.