harry potter 7: what hapend?

When Voldemort cast a killing curse at Harry Potter, he killed the Voldemort inside Harry Potter (Harry is one of the Horcrux). This is what said in the book. Actually Draco didn't kill Dumbledore. Dumbledore knew that Draco will attempt to kill him, so he asks Snape to kill Dumbledore. Dumbledore planned this to give the elder wand to Snape

As Infolancer has accurately explained, Voldemort had never been the master of the elder wand. The Elder wands true master had become Draco when he disarmed Dumbledore against Dumdledore's will whereas Snape was ORDERED to kill Dumbledore. Therefore mastery over the most powerful wand in the world had passed to Draco, not Snape. Voldemort used the Elder wand to attempt to kill Harry Potter, when Harry Potter was the true master of the wand, as Harry had defeated Draco months before the battle of Hogwarts therefore ownership had passed to Harry. So the conclusion was entirely predictable: The Elder wand would've destroyed Harry's soul (Voldy's soul would be untouched since the Elder wand never harms its master) had Voldemort beat Draco months ealier and not Snape. The simple answer to your question is: the Elder wand can't harm its master which saved Harry's life. Voldemort had actually killed himself twice LMAO! For such a powerful wizard, Voldy was too ignorant to understand how the Elder wand worked. If he was there personally, he'd have killed Dumbledore and become the master of the wand. If that happened Harry Potter would've ended with Voldemort as the winner.

Now as Harry finds out in Severus's.. or rather Professor Snape's.. Memory, that a part of Voldy (Voldemorts) soul was concealed in him the day he tried to kill him. The curse had backfired and Harry's brain was connected to that part and so that gave him the ability to speak to snakes, to look inside Voldemort's mind. They had a connection with the wand also, but that is another topic.. Well anyways, So.. When Voldemort tried to kill Harry while he was in the forest, he.. well.. destroyed the part of soul that was inside Harry, and Harry was still alive.. About Dumbledore.. Just I'm not very sure, that all happend in his head, something about Dumbledore actually telling him about everything, he was like in a dream. For the Draco part, if you remember, When Draco burst inside the Astronomy tower, he shouted "EXPELLIARMUS" and disarmed Dumbledore. To win a wand from the owner, he has to defeat the opponent, Draco made Dumbledore wandless, and hence had beaten him in the 'duel'. So, Draco was the owner of the Elder Wand, But Harry had defeated Draco, and then he was the owner of the Elder Wand, But Voldemort did not know this - I think this is one of the many reasons Harry wasn't killed when Voldemort tried that (In the 7th book) Hope this helps..