I'm not sure if you can push them back in or not, but I would assume that if the chick was stepped on hard enough to cause this, there's probably a ton more internal damage that likely can't be repaired. If it were me, I would have the chick put down...I hope someone else has better information or perhaps some advice for you. Good luck!
I am so sorry this happened but the kindest thing you can do is put the chick out of its misery. The external intestines are only the visible damage. There is no telling how bad the organs may be on the inside. There is not much hope. I know how difficult making this kind of call is.