Harry decides to go for the horcruxes, he succeeds in the end after he gives himself up to Voldemort,
Turns out Snape was actually a double agent ultimately placed to bring down Voldemort, in vengeance for killing Harry's mother, Snape was in love with her you see.
Voldemort kills Snape to become the master of the elder wand but it is ineffective as the elder wand's allegiance was taken from Dumbeldore given to Malfoy, whom, Harry disarmed and so gained the allegiance of the elder wand and it's power.
Voldemort uses avada kedavara which instead of killing Harry kills the part of Voldemorts soul latched onto Harry because Harry is a Horcrux.
At this point the final Horcrux is Nagini the snake which Neville kills with gryffindors sword.