Bruce Kolk wants to find a missing app:
I was repositioning an app icon to put into another folder. When it got to the home screen, I was holding to the left edge—when it suddenly disappeared. I can search for it, open it, but can’t find the icon to put it in the appropriate folder.

iOS Spotlight shows you the folder that encloses an app, if any.
If you use Spotlight to find the app (swipe down, enter its name), you’ll see next to the results what folder it’s in. Check that folder.
But I suspect you’ve already done that. In that case, you need to uninstall and reinstall the app, which will delete all associated data. Use Settings > General > Storage & iCloud Usage > Storage to find the app, tap it, and then you can tap Delete App. (If you sync with iTunes, you can also delete via iTunes.)
Many apps sync via the cloud or offer some form of data backup, so I hope that the app in question is one of those.
However, if it’s not, you might have to live with launching via Siri or Spotlight.
Update: This article originally lacked a complete explanation of deleting an app that couldn’t be found on a home screen.
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