Some spoilers ahead! If you haven't seen The Force Awakens, I highly recommend it before reading the article.
Also, I want to make you know that that all this is a FAN THEORY, so it may be right, maybe not. Okey, let's go:
Everything started a long time ago, when Luke started training force-sensitive beings, like his nephew Ben Solo and Rey, his own daughter. As family, the two where very strong in the ways of the force, but also, very united. So, as Rey was growing, Ben noticed she had an incredible power, beyond his own habilites. Ben had trained hard to became what he was, but Rey was foreshading him. Also, the fact that Rey is a Skywalker when him is a Solo-Organa, make him jealous and started looking for more power. That's how he was found by Supremo Leader Snoke, who telled him about the Dark Side and of course, about Vader, who was a mysterious figure, with Luke telling about his father as less as posible.
Luke, beeing the most powerful Jedi alive, sensed Kylo's turn, so he erased Rey's memories and sent her to Jakku (That's why we dont see the face of Rey's parents, because she don't remeber them!). At this time, Luke has plans to return for Rey.
So, by the time Luke is gone to protect her daughter, Ben now Kylo and his Knights of Ren flew to the Temple and killed every apprentice Luke had. Im supposing Kylo had 15 years when this happened.
When Luke returns home, he sees all the destructiondestruction Kylo Ren has done. He feels horrible, so he start beliveing the Galaxy will be better with out him. So he goes on hidding, but if he is needed once more, he left a map un his R2D2 unir to track him. R2 goes to sleep and Luke flyes to Arch-To, the green planet we saw at the end of Episode VII.
By the same time, Lando Calrissian and wife are celebrating the born of a new baby, when they are attacked by the First Order. They where looking for Luke Skywalker's old lightsaber, which is stored somewhere inin Cloud City. They maybe killed Lando and took his baby to turn him in a soldier (FN 81-27 a.k.a Finn). This is when Maz Kanata makes her appearance, taking the lightsaber to a safe place.
15 years later, Rey shows in Maz Kanata's Home, and it's calles by Luke's lightsaber. When she touches it, she is not having a vision, she is remembering trought her father's memories, Luke Skywalker's memories!
That's why she doesn't want to return to Jakku after this, and that's why Kylo Ren didn't killed her. He was atonished that Rey is still overpassing his powers without training! Also, we know that original script says Supreme Leader Snoke says to Rey to kill Kylo, maybe trying to turn her into his new apprentice (Much like Emperor trying to make Luke kill Vader) and then the ground rips un two, separating them. (Personal trought: Luke did that to prevent Rey killing Kylo)
And you know the rest, Rey flyes to Arch-To and finds Luke, who seems concerned and surprised of seeing Rey there.