Okay, do you still have the shell? The best thing to do is going to be to put him back in the bottom half of the egg if his yolk isn't ruptured or damaged. I had a duckling do this to me once and this was the solution:
What I did was cut the corner off a Ziploc bag, push her back into her shell, wrapped a wet paper towel around the shell to provide moisture, and put the whole thing in the bag. I pulled her head through the corner of the bag, and voila! Everything stays moist, she can't pull away from the yolk too early, and the next day, she was good to go.
Ducklings with those problems either recover or they don't, but usually they don't. While you can carry them feed and water, and they will grow, they'll eventually just die from not being able to move around. If they do manage to get some leg movement going, they can recover. It's pretty unlikely, in my experience.