What is my duty towards my sister who has abandoned all Islamic acts of worship and lives a life contrary to the religion, exhibiting negative behavior towards her family, and refusing advice or going to a doctor or a ruqyah practitioner?

We advise praying for her guidance, taking her to a ruqya practitioner (for Islamic exorcism) as what she is experiencing might be sorcery, and having her examined by a devout Muslim psychiatrist. We do not recommend abandoning her, lest she become more immersed in her current state. Rather, it is better to maintain some level of relationship with her.