Dua 37 To fulfill legitimate desires or during times of difficulty, recite this supplication: (Surah Al-Anbiya (21), Verse 87)

لَّآ إِلَـٰهَ إِلَّآ أَنتَ سُبْحَـٰنَكَ إِنِّى كُنتُ مِنَ ٱلظَّـٰلِمِينَ

Laaa ilaaha illaaa Anta Subhaanaka innee kuntu minaz zaalimeen.

There is no god except You! You are immaculate! I have indeed been among the wrongdoers!

(Surah Al-Anbiya (21), Verse 87)

This supplication is called "Ayat-e-Kareema".
This is the supplication made by Prophet Yunus (A.S.) when he was swallowed by the fish and found himself alone in terrifying darkness within its belly. Allah accepted Prophet Yunus's (A.S.) prayer and granted him deliverance. This is that prayer.
When a servant recognizes his own faults and declares Allah's purity, His mercy becomes manifest.
Method - To fulfill lawful desires or seek relief from troubles: Perform two rak'ahs of nafl salah, Recite this dua 100 times, For specific needs, To be cured from illness, To accomplish any task and For righteous hopes.
Method - For healing from illness, accomplishing important tasks, or fulfilling virtuous hopes:
If one recites this supplication 1,50,000 times in a single sitting, success will be granted by Allah's will (Insha'Allah).
Whenever any calamity strikes - affliction, storm, earthquake and similar adversity - continuously recite this dua.