A person completely controlled by an evil spirit is called as possessed.
The detail given below is according to Ulama & Islamic Scholars & not from Hadees.
Recite the above verse of Chapter 38 Surah Saad verse no. 34 for 7 times in the left ear of possessed person the evil spirit leaves away.
[Cure of our worries from Holy Quran, by Maulana Muhammad Shafique page. 15]
Also recite First 5 verses of Chapter 72 Surah Jinn verse 1 to 5: -
If the Jinn haunt a house or a person or there is doubt of it, then recite Chapter 1 Surah Faateha, Aayatul Kursi & first 5 verses of Chapter 72 Surah Jinn, then blow on water & sprinkle the water on the affected person.
[Cure of our worries from Holy Quran, by Maulana Muhammad Shafique page. 16]