I don't really know what to say here. Maybe a little common sense:
Buy a crampon bag. Put the crampons in the bag. Put the bag that now contains the crampons in your pack. Avoid dropping your pack, the bag that contains your crampons, or your crampons themselves.
Personally, I go for the no-bag-crampons-on-the-outside-of-the-pack approach, but it sounds like this failed you. Better luck next time.