viewtopic.php?f=25&t=3
This article covers the basics. You've said its been over two weeks, so it should be alright to try and get a look into the nest to see if any of the babies survived. I'll warn though as that thread says, you know the babies are alive by the chirping and squeaks, not knowing how long you are in the room with them, it could be possible you're just not around when they are awake and active, or that its come to the grim conclusion. But being its been two weeks, I'd take a look, and keep us updated.