This is not a story but a challenge.
Okay so it must begin like this. 25 and up years old Harry is in a post-apocalyptic future where Voldemort managed to destroy most of the world. After their final clash Harry is then sent back into the past in his younger body, but all of his gear/magic have traveled back with him.
Ok so requirements:
1.)The future must have nuclear fallout and be destroyed with very few survivors(can have mutants).
2.)Harry must kill Voldemort.
3.)All of Future Harry's gear must end up in the past with him(clothes,weapons,ect).
4.)Dumbledore must be at least slightly manipulative.
5.)Harry must hate or at the very least slightly dislike Snape and Dumbledore.
6.)Harry must have some reaction with his horcrux.
Do whatever you please with Ron and the Weasleys. Bash or don't bash Dumbledore it is your choice if he is completley good, misguided, or flat out evil.
And finally have fun.