Why do you think he was "too harsh"? He announced up front that no late work would be accepted (you could have dropped the class at that point if you felt that was not acceptable.). You submitted your paper late; you got a zero. How is this *his* fault?
If, *before* the paper was due, you knew you needed an extension, you needed to contact him about it (again, *before* the paper was due). If he was ignoring your e-mails, you needed to call him or contact him in person. That said, unless you were actually hospitalized, you should have had no expectation that he would grant the requested extension.
(And if the reason your paper was late was because you *were* actually hospitaized, bring him the documentation and I'm sure he'll grade your paper).