Check the App Library: swipe left on the Home Screen until you reach App Library
Search in App Library: open App Library and use the search bar to find the app
Check if the app is hidden from the Home Screen: Settings → Home Screen & App Library → App Library Only (and ensure it’s not set to hide the app)
Check Screen Time limits: Settings → Screen Time → Content & Privacy Restrictions → Allowed Apps (or App Limits)
Check if the app was offloaded: Settings → General → iPhone Storage → select the app → Reinstall App (if shown)
Check for deleted apps: search for the app in the App Store or App Library
Check if the app is in a folder: swipe through Home Screens and folders to locate it
Check if the app is restricted via parental controls: Settings → Screen Time → Content Restrictions → Apps (and confirm the app is allowed)
Check for a hidden purchase/download: App Store → profile icon → Purchased (or Family) and download again if available
Check for a missing Home Screen page: press and hold on the Home Screen → tap page dots → ensure the page containing the app is enabled
Check for iOS search results: swipe down to open Spotlight Search and search the app name
Check for app usage restrictions by VPN/MDM (if applicable): Settings → General → VPN & Device Management (or Device Management)
Restart the iPhone: restart device and then re-check App Library and Search