Caring For A Duck Egg?

There's a duck nest by my work, and the mother had been sitting there for almost 3 weeks. 1 egg hatched that we saw. This morning I looked for it and she was gone; someone had walked through her nest and stepped on the hatched baby. She hasn't been back all day. Will the eggs survive? Is there anything I can do?

By Concernedbirdguy from Brockville, ON