I'm sorry to hear about that! Do you have any idea what might of caused that? Angelfish are not easy to breed so it may take a few tries until you can successfully breed them. Best of luck, you'll probably get eggs again soon.
if you have other fish in the tank then boom they got to them.. when they are young they are very finicky and need daily water changes after feedings and should be fed 3 times a day.. and should be fed brine shrimp because they have very small mouths...
imo angels are easy to breed under the right circumstances and i'm guessing that the water stats were not good for the young.