What should I do for my deceased father, when I was disobedient to him and refused to see him? And what is your advice to me to alleviate my guilt and illness?

The questioner must strive to repent to Allah and make up for what she missed in honoring her father, by supplicating for him, seeking forgiveness for him, giving charity on his behalf, paying off his debts, maintaining ties of kinship on his side, and honoring his friends.