As said, it happens to the best(and worst) of us.
I recall a friend once(name withheld to protect the guilty, as he is also a member here) who brought me his Lee 9mm sizing die with a case stuck in it. He had been loading 38 specials and changed dies, but forgot to change the shell holder-an easy enough mistake to make, and I've done similar things.
Unfortunately, before he brought it to me he had tried numerous methods to extract the case-most notably pulling on the case head with a pair of vice grips while his dad held the die body with another pair. Somewhere in the process, he'd manage to bend the decapping pin(those of you who have used Lee dies know how difficult this is to do).
Fortunately, using the "hammer and punch" Lee method, the case popped right out, and I think if he gets another stuck case he'll do it that way.
Unfortunately, his previous attempts had messed up the die threads, as well as the threads on the collet that holds the decapping pin. Even with the case out, the die was essentially unuseable, and he ended up buying a new sizing die.
I've stuck my fair share of cases even in my relatively short year and a half of reloading. Every one has been a learning experience, and once you get this case out, I'd encourage you to use it as such as well!