Well it depends on exactly what you mean. Do you mean that you literally cannot feel anything down there, as in your entire vagina and all external genetalia like the lips and clitoris are numb? What about tampons (if you use them)? It is rare that a woman is completely and totally numb down there.

Did you masturbate before you started having sex? Can you get stimulation from your clitoris?

or do you mean that you can't orgasm? if this is the case you are no alone. alot of women can't orgasm from intercourse alone