Till the time Warqa bin Naufal was alive, he used to make revelation for Muhammad. But once he died, then immediately revelation stopped.

Why?

And revelation ceased to come for the next 3 years (link). 

Sahih Bukhari, Hadith 6982:
The angel came to him (i.e. Muhammad) in it (i.e. Cave of Hira) and asked him to read. The Prophet replied, "I do not know how to read." (The Prophet  added), "The angel caught me (forcefully) and pressed me so hard that I could not bear it anymore. He then released me and again asked me to read, and I replied, "I do not know how to read," whereupon he caught me again and pressed me a second time till I could not bear it anymore. He then released me and asked me again to read, but again I replied, "I do not know how to read (or, what shall I read?)." Thereupon he caught me for the third time and pressed me and then released me and said, "Read: In the Name of your Lord, Who has created (all that exists). Has created man from a clot. Read and Your Lord is Most Generous...up to..... ..that which he knew not." (96.15) Then Allah's Messenger  returned with the Inspiration, his neck muscles twitching with terror till he entered upon Khadija and said, "Cover me! Cover me!" …  Khadija then accompanied him to (her cousin) Waraqa bin Naufal , who during the Pre-Islamic Period became a Christian and used to write the Arabic writing and used to write of the Gospels in Arabic as much as Allah wished him to write. He was an old man and had lost his eyesight. Khadija said to him, "O my cousin! Listen to the story of your nephew." Waraqa asked, "O my nephew! What have you seen?" The Prophet  described whatever he had seen. Waraqa said, "This is the same Namus (i.e., Gabriel, the Angel who keeps the secrets) whom Allah had sent to Moses. I wish I were young and could live up to the time when your people would turn you out." Allah's Messenger  asked, "Will they turn me out?" Waraqa replied in the affirmative and said: "Never did a man come with something similar to what you have brought but was treated with hostility. If I should remain alive till the day when you will be turned out then I would support you strongly." But after a few days Waraqa died and the Divine Inspiration was also paused for a while and the Prophet  became so sad as we have heard that he intended several times to throw himself from the tops of high mountains and every time he went up the top of a mountain in order to throw himself down, Gabriel would appear before him and say, "O Muhammad! You are indeed Allah's Messenger  in truth" whereupon his heart would become quiet and he would calm down and would return home. And whenever the period of the coming of the inspiration used to become long, he would do as before, but when he used to reach the top of a mountain, Gabriel would appear before him and say to him what he had said before.

This is strange. What did the death of Warqa have to do with the revelation that it ceased for 3 years? 

Islam apologists don’t have any answer for this. At maximum, they present the following excuse from Ibn Hajar al-Asqalani (link):

" وَفُتُورُ الْوَحْيِ : عِبَارَةٌ عَنْ تَأَخُّرِهِ مُدَّةً مِنَ الزَّمَانِ ، وَكَانَ ذَلِكَ لِيَذْهَبَ مَا كَانَ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَجَدَهُ مِنَ الرَّوْعِ ، وَلِيَحْصُلَ لَهُ التَّشَوُّفُ إِلَى الْعَوْدِ "

Translation:
The cessation of revelation refers to it being delayed for a period of time. This was so that what the Prophet felt of fear might dissipate, and so that he would long for its return.

Let us analyze this excuse by Islam apologists:

  1. Why did Muhammad keep on fearing for the next 3 long years? 
  2. But the tradition of Bukhari tells that not only Muhammad became free of that fear, but he longed so much for it that he used to climb the mountains, in order to commit suicide, while he didn’t receive the revelation.
    How could then Muslims hide behind the excuse that Muhammed kept on fearing for the next 3 years and that is why revelation was ceased?
  3. Another question is about the “wisdom”, why did Jibrael have to frighten Muhammad by pressing him so hard that he could hardly breath?
    No Muslim ever answers the wisdom behind this act.
    When Jibrael came to Mariyam (Mary) or to other prophets, he didn’t frighten them so that they kept on fearing him for the next 3 years. Why did then Jibrael do it to Muhammad only?
    There is absolutely no logic in doing this act, except this that Muhammad was initially unable to make a revelation without Warqa, and thus he stopped the claim of revelation for this period of time, and later he took refuge in this excuse that revelation was ceased for this period while he feared Jibrael, as he pressed him forcefully. 

Another problem is this, while Islam apologists fabricated these excuses at their own, therefore more contradictions occurred in them. For example, the following tradition from Sahih Bukhari tells that after the delay (of 3 years), when Jibrael again appeared with revelation, then again Muhammad became fearful of him as he became fearful of him the first time. 

Sahih Bukhari, Hadith 4926:

Narrated Jabir bin `Abdullah:

That he heard Allah's Messenger (ﷺ) describing the period of pause of the Divine Inspiration, and in his description he said, "While I was walking I heard a voice from the sky. I looked up towards the sky, and behold! I saw the same Angel who came to me in the Cave of Hira', sitting on a chair between the sky and the earth. I was so terrified by him that I fell down on the ground. Then I went to my wife and said, 'Wrap me in garments! Wrap me in garments!' They wrapped me, and then Allah revealed: "O you, (Muhammad) wrapped-up! Arise and warn...and desert the idols." (74.1-5) Abu Salama said....Rujz means idols." After that, the Divine Inspiration started coming more frequently and regularly.

So, question is, if even after 3 years of delay, Muhammad still feared Jibrael, what was then the purpose of this pause in the revelation?

This refutes the Muslim excuse that revelation was ceased for this period of time, so that Muhammad didn’t fear Jibrael anymore. 

Other excuses from Islam apologists is this that some Scholars said that it was not the period of 3 years, but of 12 days, or 40 days only. But firstly, these scholars failed to present any authentic tradition about this claim of 12 days or 40 days, and it also goes against the tradition of Bukhari which tells us that it was long enough period in which Muhammad longed for revelation so much that he often climbed the mountain in order to commit suicide, and every time Jibrael stopped him from doing it.