I purposely removed mine. I didn't use it for a while because I would just use a double down swipe homescreen gesture. I put it back now. I can't remember exactly how I got it back. I think I might have restored it from a backup.
I don't understand what you mean. What app icons are missing?
Oh nevermind I see what you mean. Just long press and create another shortcut and you can move it back to your dock. You must have mistskingly moved it from your dock and deleted it.