To unhide apps on your iPhone, swipe left to the App Library, tap the "Hidden" folder (you'll need Face ID/Touch ID/passcode to open), then long-press the app and select Add to Home Screen, or tap Don't Require Face ID/Passcode to keep it in the Library but accessible; drag the app from the App Library to your Home Screen to place it visually.
On your home screen, swipe to the left until you get to the App Library. From there, explore the app folders to find the missing app you want to add back to your home screen.
Your iPhone apps may disappear due to various reasons, such as an iOS update, accidental deletion, or a glitch in the system. How can I find the missing apps on my iPhone? You can check the App Library, search for the missing app using the search bar, or reset the home screen layout to find the disappeared apps.
To add an app back to your home screen (iPhone or Android), find it in the App Library (swipe left on iPhone) or App Drawer (Android), then tap and hold the app icon, and either drag it to your desired spot or select "Add to Home Screen" from the menu that appears.
To get hidden apps back, use your phone's search function or check specific "Hidden Apps" folders in the App Library (iPhone) or Home Screen settings (Android); for iOS, swipe to App Library > Hidden Folder and use Face ID/passcode; for Android, go to Home Screen settings > Hide Apps and uncheck the app, or use Search/App Drawer settings.
Android
Unhide an app
You can stop hiding an app so that you can see it. Go to the Home Screen. Swipe left past all your Home Screen pages to go to App Library. Tap the Hidden folder at the bottom of App Library, then authenticate using Face ID (or Touch ID or a passcode).
Solution
To add an app back to your home screen (iPhone or Android), find it in the App Library (swipe left on iPhone) or App Drawer (Android), then tap and hold the app icon, and either drag it to your desired spot or select "Add to Home Screen" from the menu that appears.
There are two main reasons why you might have a hidden app on your iPhone: You've deliberately hidden an app yourself, because you don't want someone looking over your shoulder and seeing a sensitive app's icon on your home screen. Someone's secretly installed an app on your iPhone.
Unhiding Apps Using Default Settings