Hi Noha, great question! In this example, I would respond "no, hardly anything." You could say "hardly any" only if the question was asking about a specific piece of knowledge. For example, if the question was, "do you know any computer codes?" you could respond with, "no, hardly any (computer codes)" and it would be correct. Since the question only asks about general level of knowledge (know much), you should use the pronoun "anything." You could also respond with the same phrase in the question: "no, I don't know much about computers." I hope that helps. Pronouns like this can be tricky!