In the name of Allah, the Most Gracious, the Most Merciful.
Call upon Me; I will respond to you.
In this noble verse, Allah Almighty is saying, "Pray to Me, and I will answer you." Sometimes it happens that we want something and want it with all our intensity, but we do not get it in time. Then we try to pray during the time that has been specified for acceptance, and we pray to Allah with full hope that this is the hour of acceptance of prayers, and my prayer will be accepted. We do all those things with full intensity that will get us that thing, and we keep praying. Then sometimes it happens that the time we need it runs out. Then at that time, negative thoughts start arising in our minds, that Allah does not listen to our prayers, He does not accept our prayers, even though He knows how intensely we wanted that thing, yet Allah did not give it to me, etc.
But alas, we never think why Allah did not bless us with that thing. Was it not for us, or were we even worthy of it?
While we should think about this, it is a matter of contemplation why Allah did not bless us with that thing, while Allah Almighty Himself has said in His Holy Book, the Quran, "Call upon Me; I will respond to you." So why is it that our heartfelt prayer is not accepted? So this is not the time to create negative thoughts in our minds, but it is the time to think and understand that the Lord who knows us more than our jugular vein, if He has not blessed us with that thing, then there must be some wisdom, some expediency in it. Or it may also be that what we are desiring is not better for us, because we are the ones who seek the best, and Allah is the One who does the best.
Prayers are accepted, if not today, then tomorrow they will be, but they will definitely be when the time is right. We can learn this from Hajra (peace be upon her), who was in a desolate desert with an innocent child, Hazrat Ismail (peace be upon him), when her provisions ran out, and Ismail (peace be upon him) started crying with thirst and hunger. Hajra (peace be upon her) went around Safa and Marwa in search of water and kept praying to her Lord continuously. Allah Almighty accepted her prayer, but it took time. When her prayer was accepted and the spring of Zamzam gushed forth from under the feet of Hazrat Ismail (peace be upon him), Hazrat Hajra (peace be upon her) had completed seven rounds of Safa and Marwa. She neither stopped praying nor complained to Allah, and Allah Almighty liked the effort and patience of Hajra (peace be upon her) to such an extent that He included her action in the pillars of Hajj and Umrah, without which no one can perform Hajj and Umrah. This is what they say, Allah is with those who are patient.
Therefore, we should keep praying. Prayers will be accepted, and the longer it takes for prayers to be accepted, the better and more beautiful they will be in shape. The summary of the matter is that we should pray and with full hope and humility, and we should not be afraid of the delay in acceptance, and we should be patient, understanding that what we do not get even with a million prayers was not for me, because Allah is with those who are patient. We should not complain. We pray to Allah, O Allah, Lord of the Worlds, accept our prayers and grant us patience 
and grant us the ability to do so. Amen, O Lord of the Worlds.