There are many great Du'a and Quranic verses in this regard e.g.
1. Ayatul Kursi, 3 times or 5 times or 7 times..
2. Sura Al-Hamd, 7 times or 40 times or 70 times.
3. Sura Tawheed, 12 times or more.
4. Night Prayer (Namaz e Shab) Salatul Layl.
5. Ziyarat Ashura.
Wassalam..