Timeline of Events
Everything in the Harry Potter series has happened. The only few things which didn't happen are at the end of book 7. After getting a hold of Hufflepuff's cup, Harry Ron and Hermione went around the country trying to find a way of destroying it without the sword. Eventually they did manage to destroy it. During this time Hogwarts was crumbling, Voldemort's grasp on the school was fading as the Carrows and Snape fled the school. The reason for fleeing, they say, was that there was too much resistence, even the teachers started fighting back after a while. Voldemort, who was too busy trying to catch Harry Potter, ignored the school which eventually went back to its original state. The ministry was soon to follow and then in the year 2000, Voldemort "lost" a fight and went into hiding. During this fight, Harry discovered what he had to do to kill Voldemort, (kill himself) but he wanted to make sure that all of Voldemort's Horcruxes are destroyed first. But Voldemort was torn and his allies were either dead or fleeing. He went into hiding, abroad to try and regain his power, create more Horcruxes and come back, stronger than ever.
Luckily for Harry, he did manage to destroy all of Voldemorts Horcruxes (except for Nagini and the one inside of him) and while Voldemort went into hiding he trained as an auror. Two years later, Voldemort came back with more followers, and a stronger power than ever before. But the wizarding world had been warned and made sure that they were protected greater than before. That didn't mean that Voldemort didn't try to take over though.
Now, the wizarding world is getting tired of its endless war against Voldemort, and Harry Rona and Hermione are trying over and over again to destroy Voldemorts Horcruxes and then Voldemort himself.