ok. Don't just chuck them, first hold the eggs up to a light.......... you need to learn to see if the eggs have chicks in or are clear (unfertilised). Eggs that are clear will have a translucent appearance, the ones with chicks in will look solid. As they've been sitting for 24 days they're either dead in the shell or clear. One at a time hold them up to a light and decide if they are clear or not, then break the egg to find out whats inside. This will learn you what to look for in the future, you'll be able to tell if the eggs are any good after they've been sitting for 10 days. Why they haven't hatched I cant say.