Usage patterns
どんなに〈形容詞〉てもno matter how [adjective] it is
No matter how cold it is, he runs outside every day.
どんなに〈事〉かexpresses how [adjective/verb] something is, with emotional emphasis
No one understands how sad he is.
どんなに〈動詞〉てもno matter how much one does [verb]
No matter how much she studies, she always says she isn't confident.
どんなに〜だろうexpresses wondering how much/how [adjective/verb] something must be
If I pass, how happy I would be!