What launcher / home replacement are you running? If its Nova, long press on the desktop and choose "nova actions" - then choose app drawer, once the shortcut is created you drag it to your tray.

If its another launcher it probably has a similar ability to create action shortcuts. Someone else will have to chime in on your particular version as I don't know how Apex or other launchers handle it.

 

long press home screen and add it i deleted mine the other day, you cant long press where it should go just in middle of screen