Welcome to BYC. Glad you decided to join our flock. I assume you're talking about chicken eggs? If they haven't hatched in 28 days, all the chicks in them are dead and they are not going to hatch. Sadly, it's time to throw them out. ( Please feel free to ask any questions you may have. We are here to help in any way we can.
Glad you could join the flock! What are your eggs? Chicken, duck or other? Different poultry have different incubation periods. Was the bird in the egg you broke open alive? What incubation methods have you used? Temp? Humidity? What kind of incubator are you using? Still air? Forced air?
Did you turn the eggs? When did you stop turning? How and for how long were the eggs stored prior to incubation?
So many things can play a part in incubation failures even before the eggs are incubated.
Hope you are able to find out what happened and your future attempts are a success.
Welcome to BYC and the coop! There's a lot of great peeps here! Feel free to ask lots of questions. But most of all, make yourself at home. I'm so glad you decided to joined the BYC family. I look forward to seeing you around BYC.