On some recent devices (HTC X9, LG G5, Huawei P8, MIUI Rom,...), manufacturers decided to remove the app Drawer on their devices. Some rumors also suggest that Google itself removes it.
(The app Drawer is the list of installed apps, from where you can drag an icon and put it on your desktop, that's the main difference with the Apple iPhone launcher, and a great addition to Android)
You can install an alternative Launcher (Nova Launcher, Action Launcher, Apex,...) to fix this annoying issue, but this will replace completely your manufacturer launcher.
If you want to keep the original one, you can install App Drawer. This application is a simple shortcut, looking exactly like the Launcher icon, and that will show you a list of installed apps and let you launch them.
PRO TIP: if you want to close the drawer, use the home button, not the back button, the application will be way faster like this ;-)
I still haven't found the perfect solution to hide your unused icons, except to put them all in a garbage folder and try to hide it somewhere in a corner of a screen.
More features to come (Theme, hide apps,customisations,...)
Any suggestion? Feel free to send me an email. Any suggestion is always welcome!