How to find that missing App that you know you have on your iPad

How to Search for an app on IOS 8 

First go to settings and then General then Spotlight Search

Make sure Applications is ticked

With the newest OS go to the search screen and search for - (minus sign).  Or hyphen on touchpad but most characters will work on the .?123 button

If Applications is unticked the same action above will instead show your Music  Tracks instead.

Once you have a list of your apps the folder will be named on the right hand side if you have created a folder.

Tapping on an App will open it of course.