Have you heard of anyone who died then returned to life to say that Hell and Paradise are real? I need substantial evidence.

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

A true Muslim does not need one of the dead to return to life and tell him about what he saw after death. It is enough for a Muslim   to know that Muhammad, sallallaahu ‘alayhi wa sallam, the faithful and the honest Prophet, whose heart and insight were purified by Allaah the Almighty, went to that world and saw the bliss that Allaah The Almighty  has prepared for the people of Paradise, and the torment and shame that He has prepared for the people of Hell.   Then he, sallallaahu ‘alayhi wa sallam, returned and told everyone about what he had seen in detail. Certainly, what the Prophet, sallallaahu ‘alayhi wa sallam, saw is more trustworthy than what we would see with our own eyes, if we were able  to do so.

One of the righteous predecessors once told his friends that he had really seen Paradise and Hell in this world because the Prophet, sallallaahu ‘alayhi wa sallam, had seen them, arguing that the eyes of the Prophet, sallallaahu ‘alayhi wa sallam, were more trustworthy than his own eyes. 

With regards to the substantial evidence that you ask for, . Thus, it is impossible for anyone to provide substantial evidence of their factual existence, mainly because believing in the existence of the unseen is part of our belief as Muslims.

However, we can provide you with stronger logical  evidence:

-        Believing in Paradise and Hell is pursuant to our belief in Allaah The Almighty. It is possible that Allaah, the utterly Just, created this world, which is a stage for tragedies, injustice and brutality, and then for the world to end without having avenged those who suffered injustice from their aggressors, or from those who were killed on their killers? In other words, the world cannot end without rewarding good people and punishing evil ones. If matters would go this way, despair, disbelief, immorality and wickedness will prevail.  Therefore, there should be a day when the Just God judges his creatures. Allaah The Almighty Says (what means): {So whoever does an atom's weight of good will see it, * and whoever does an atom's weight of evil will see it.} [Quran 99:7, 8].  

A true believer  also knows that Allaah The Almighty does not create anything uselessly.  Allaah The Almighty Says (what means): {Then did you think that We created you uselessly and that to Us you would not be returned?"} [Quran 23:115].  This belief means that Allaah, the All Wise, did not create man uselessly without obligations and limitations and, consequently, without reward and punishment.

-        Believing in the existence of Paradise and Hell is pursuant to our belief that the Quran is the word of Allaah The Almighty.  The Quran speaks about Paradise (and its moral and material bliss) and  Hell (and it moral and material torment). The Quran also provides evidence of the factualness of the resurrection, reckoning and reward and punishment.  The evidence includes:

1.       Proving the possibility of resurrection by comparing it to the initial creation; Allaah The Almighty Says (what means): {And they will say, "Who will restore us?" Say, "He who brought you forth the first time."} [Quran 17:51].  

2.       Proving the possibility of resurrection through the phases of creation. Allaah The Almighty Says (what means): {O people, if you should be in doubt about the Resurrection, then [consider that] indeed, We created you from dust, then from a sperm-drop, then from a clinging clot, and then from a lump of flesh,} [Quran 22:5] Thus, Allaah The Exalted, who was able to create man through different phases, is able to recreate him again so as to dwell in the eternal bliss or the eternal torment.

-        Believing in the existence of Paradise and Hell is related to our belief in the Prophet, sallallaahu ‘alayhi wa sallam, that is: if we really believe that Muhammad, sallallaahu ‘alayhi wa sallam, is the Messenger of Allaah, then we  believe all that Allaah The Almighty revealed to him, including religious obligations and prohibitions, the existence of Paradise and Hell, and the status of the people of Paradise and the people of  Hell.

-        Furthermore,  despite the fact that the followers of all religions disagree on certain aspects, they all believe in the existence of Paradise and Hell, regardless of them having different names.  On the other hand, atheists and irreligious people who deny the existence of Paradise and Hell do not ground their opinion on any evidence whatsoever. Therefore, the Quran calls their belief  "mere assumptions." Allaah The Almighty Says (what means): {And they say, "There is not but our worldly life; we die and live, and nothing destroys us except time." And they have of that no knowledge; they are only assuming.} [Quran 45:24]

-        Finally, we remind the questioner that guidance is only in hands of Allaah The Almighty, therefore there are many people who have not only seen evidence but, instead, have witnessed inarguable miracles; nevertheless, they were deprived of the right guidance.  Therefore the person who has been guided to the truth from the start should thank Allaah The Almighty for guiding him and ask Him to give more guidance and certainty. Finally, contemplate the following verses.  Allaah The Almighty Says (what means):

•        {And they swear by Allaah their strongest oaths that if a sign came to them, they would surely believe in it. Say, "The signs are only with Allaah ." And what will make you perceive that even if a sign came, they would not believe. * And We will turn away their hearts and their eyes just as they refused to believe in it the first time. And We will leave them in their transgression, wandering blindly.} [Quran 6:110]

•        {And they swore by Allaah their strongest oaths that if a warner came to them, they would be more guided than [any] one of the [previous] nations. But when a warner came to them, it did not increase them except in aversion.} [Quran 35:24]

Allaah Knows best.