How do I find the app icon for iphone

Suddenly my App Store icon is missing from my icons showing on any of my screens

Check for it under the App Library. Next to the last page of the Home Screen. If it is in the App Library Touch, Hold and Drag the icon to Home Screen. That's it.

Swipe left through the apps Home Screen until you see the last screen which is App Library. Search for the application you’re looking for, tap, hold and drag that application icon to home screen