Do you mean that you removed it from the "Dock" list of app icons?

The Dock is just a link to the apps, so removing it doesn't move the app, itself. A right click (or control-click) on an icon in the Dock brings up this menu:

(I have my Dock on the side of my screen instead of the bottom. While taking this screenshot, I accidentally removed my own Photos icon from my Dock!)
The Photos app is located in the Applications folder:

Do you find it there? You can grab it and drag it to the Dock
You can also get to the Photos app by using Spotlight--tap command-space and type Photos.
I hope this was what happened. Let us know…