How do I find hidden apps

Welcome to Android Central! What do you mean by hidden apps? Were they hidden in the App Drawer? Do you have any kind of app locker app installed?
 
Look up the app "access lock" - I think that's what you might be asking? It allows you to control permissions for apps, and is hidden.
 
If you have hidden apps (I have done this on apps that I couldn't disable). go to app drawer,settings,hide/show apps. Find the ones that have a check mark & uncheck if want to unhide, then press "check mark"