What is the ruling on not speaking to one's father for a long period, while not forgetting his rights, and is this considered a major sin or filial disobedience?

Abandoning one's father is an act of disobedience (ʿuqūq), and it is among the gravest of major sins, as stated in the Hadith: "Shall I not inform you of the greatest of major sins?" We said, "Yes, O Messenger of Allah." He said, "Associating partners with Allah, and disobedience to parents." It is not permissible to abandon one's parents, no matter how much they might mistreat you. Rather, one must treat them with kindness and companionship with honor, as Allah the Almighty says: "And accompany them in the world with honor" and "and to parents, do good." It is obligatory upon you to reconcile with your father, apologize to him, treat him with kindness, and offer sincere repentance to Allah the Almighty.