We want to assure you that you won't be penalized for a failed generation. You won't be charged a credit if DALL·E 2 is unable to successfully generate an image based on your request.
We understand that not every request will be successful, and we don't want to punish our users for that. So rest assured, you can keep trying different requests without worrying about wasting your credits on failed generations.
You're only charged for successful requests. If you're looking for your generation history, you can find them on your "My Collection" page.