How can I speak to my father, who accuses me of theft and does not want to understand or speak to me?

Your father is not allowed to accuse you of theft without proof. You must gently show him your innocence, and you can seek help from some virtuous people to clarify the matter for him. You are not permitted to shun him or mistreat him because of this; rather, you must continue to honor him and treat him kindly. If he insists on shunning you after you have fulfilled your duty towards him, then that will not harm you, Allah willing.