There are numerous reasons why the response to our supplications may be delayed:
1. The weak supplication because of supplicating with weak and offensive statements
2. One does not gather his heart together on what he seeks to have at the time of supplication
3. The obstacles that impede the response of Allah The Almighty to supplication, such as consuming unlawful gains, accumulation of sins upon the heart, heedlessness, following desires and a distracted heart: "Allah does not respond to a supplication from a inattentive heedless heart." [At-Tirmithi]
Thus, any supplication wherewith one supplicates Allah The Almighty is like an arrow; the weak and elastic bow always shoots a weak arrow which fails to hit the mark. Besides, there are numerous other other obstacles to a response, like consuming unlawful gains, multiplication of sins, misdeeds and mistakes, prevalence of heedlessness, desire and distraction over the heart: how could the supplication receive an answer?
The Messenger of Allah said: "Supplicate Allah while you are certain of the response." [At-Tirmithi] That is, supplicate Allah The Almighty and be certain that Allah The Almighty will respond to your supplications.
Supplication is the most beneficial treatment of affliction. It is, in other words, the most ferocious enemy of the adversity that afflicts one in his religion, soul, property, children, family, and the Ummah (nation) of the Muslims. Supplication averts adversity, treats it, and prevents it from occurrence; and even if it takes place, supplication removes it, or, at least, alleviates its evil consequences in proportion to its strength and power.
Supplication may be stronger than adversity, and, in this way, capable of removing it, or weaker than adversity and thus, capable of reducing its evil consequences, or equal to adversity, thereupon both continue to wrestle until the Day of Judgment. [Al-Haakim]
This is why the Messenger of Allah says: "No caution could avail against fate." [Ahmad] [Al-Albaani: Saheeh] Supplication helps one aainst what has and what has not descended yet. Adversity descends and is met with supplication, and both continue to wrestle until the Day of Judgment. In confirmation of that, the Messenger of Allah says: "Supplication could avail against what has and what has not descended yet. So, stick to supplication, O slaves of Allah!"
Thus, it is incumbent on the believers to focus their attention, in these days, on the means that ensure the response of Allah The Almighty to supplication. No doubt, their sins and misdeeds have grown greatly and their deeds have been deprived of blessings. They are no longer able to approach Allah The Almighty nor get ready for meeting Him in the manner that is due to Him.
A believer must always have a way and a gate open to Allah The Almighty. Unless his Lord strengthens him, none else could ever do so and unless Allah The Almighty forgives him, no one else could ever do; unless He provides for him, none else could ever do and unless He removes difficulties from him, none else could ever do. Who could alleviate difficulties from him? Who could provide for him? Who could cure him? Who could grant him blessings in his time? Who could take him to Allah? Who could forgive him? Who could remove disaster and adversity from him? Who could reform his morals and habits? Who could accept his repentance? He is Allah, The Exalted, The Almighty, and none else.
If Allah The Almighty is not on his side, then all will be against him, and he will see life depressed and constricted, and closed in his face, and every time he tries to enter a gate, he finds it closed. In such a case, nothing could benefit him other than a sincere supplication. If one knows this, he will not consider the response too slow since one of the causes that impede the response to supplication is when one says, "I have supplicated and received no answer! "
According to a narration: "‘The slave continues to have his supplication fulfilled as long as he does not supplicate with sin or severance of kinship ties, provided that he is not hasty.’ It was said, ‘O Messenger of Allah! What is haste?’ He said: ‘It is to say, “I have supplicated again and again, and seen no response to that.”'" [Muslim]