Eyes stuck shut can happen. I've used warm water and a cotton ball to gently soak, then help open the eyes if they still haven't opened on their own a few days past when they normally should (around 10 days old).
If they have pus, it's called "nest-box eye" - never experienced that one myself, but from what I understand it's basically just a mild infection. You can clean with a really mild saline solution or ointment twice a day until it clears up.