In the last Harry Potter book, Harry destroys all of the horcruxes that Voldermort has split his life into. After destroying all of them harry knows that Voldermort is vulnerable and will easily die. He then meets up with Voldermort in front of all his friends as well as Voldermort's helpers and kills Voldermort. Before this time, Harry partially dies and goes to the land of the dead. Here, he meets his old teacher Dumbledore, who had also died in the 6th book. He talks to Dumbeldore, and then comes back to life.

An alternative ending to this book would be if Harry was able to bring his friends back to life as well when he died and entered the land of the dead. When Dumbledore was talking to Harry here, he only talked philosophy and told Harry how he should kill off Voldermort. An alternate event that could have happenned is that Dumbledore could have told Harry a method to be able to bring back all of the people that had died back to life, including his parents, Fred and George, his owl, and his other friends. The series could have even been extended for another book, in which he stayed in the land of the dead, figured out ways to bring back all the people who had died, and then come back to life to finally kill Voldemort. 

The name of the next book would be "The Death Journey", since Harry would have his own adventures in these lands that are completely unrelated to what happened in the first 6 books. Here, Dumbledore would first explain Harry that where he has entered is called the "Tunnel of the Dead", and is where people go after they die. The tunnel of the dead leads to a place called the "Otherworld", which is where people go after they die, much like Greek Mythology. he then leads Harry into the Otherworld, and shows him the place, a vast expanse of land that looks similar to the real world, but much darker and more remeniscient of death. Everyone that he sees is a ghost, with body parts that cannot be physically felt but only can be seen. Dumbledore then tells Harry that he is not really dead because he has not become a ghost, as people who die do when they enter the Otherworld. he tells Harry that he is "half-dead", like Voldermort was when Harry was a baby and repelled his killing curse. Voldermort, too, had come to this place. Dumbledore also explains that the people who find a special potion hidden somewhere in the Otherworld will be able to return to the real world, and the only way that Harry can go back is if he finds the potion. Harry questions Dumbledore about what happens when dead people drink the potion. Dumbledore tells him that dead people who find the potion will return in their ghost form to the real world. 

This leads to a series of events that Harry, Dumbledore, and Harry's dead friends go through before they find the magic potion. After they find this potion, they all drink it, go back to the real world (Harry as himself and everyone else as ghosts), and harry kills off Voldermort like he did in the real ending. However, now Harry can see his dead friends as well.