What iOS version do you have on your iPhone? iOS 14?
If so, you may have 'removed' the app from your home screen. In which case you would still be able to find the app by searching and still be able to open the app.. and it would not exist on your home screen.
If you swipe left continually on your home screen until you get to the App Library. Pull down. Locate the app in the alphabetical list. Tap/hold/drag the app back onto your main screen. Even if the app is really tucked away in a folder somewhere, doing this will pull it out from wherever it was hiding and replace it with the new one that you dragged out from the App Library.
Organize the Home Screen and App Library on your iPhone - Apple Support