I found an abandoned sparrow egg, what can i do to save it?!?!?

In my grandmothers yard their was a nest and one of the eggs hatched and their was another egg that still hadn't hatched, today she found the hatched baby bird dead by the tree on the ground close to the other egg that still hasn't hatched. i picked up the egg because obviously the mother wasn't coming back for it and am wondering if there is any thing i can do to save the egg and help it to hatch. Or maybe could it possibly already be dead, the nest was around 5ft.-6ft. from the ground. Thanks so much for any help!!!=]]]