First of all, check the spam folder of the email account associated with that blog to make sure the email didn’t accidentally get caught by your email spam filter.
Second, to cancel and refund a domain name registration through WordPress.com, I have marked this thread for Staff attention.
Third, please note that once you delete your blog, you can never, repeat never, get it back or register the same name again. So, think very carefully if you truly want to delete it. If you think you may want to use it in the future, make the blog private in the Privacy settings of your Dashboard. No one will see it unless you invite them and search engines will not find it.