The Basilisk had bit him. Dumbledore had abandoned him. Harry knew that Dumbledore wouldn't have been able to do what he did last year but even the Sorting Hat might have helped. Instead he was going to die. He hoped they didn't close the school. What would happen to the Muggleborns and people like him? He wished he wasn't dying. He was twelve. He didn't know what was going to happen. He was terrif...
The school was abandoned. There had been a memorial for Harry Potter, Ginny and Ron Weasley, and the courageous Professor Lockheart. No one knew what had happened down in the Chamber but by the time Hermione had been saved and told everyone where the Chamber was and a Parselmouth was located to open the Chamber, Ron and and Professor Lockheart had died of starvation and Harry and Ginny had been long dead. The memory of Tom Riddle had left to find the shell of his future self and had closed off the Chamber. Wizard and Muggle kind was living in fear of Voldemort. The only person who could kill Voldemort had already died at his hand. There was no hope and there was no Hogwarts.
All that was left at Hogwarts were the ghosts, those that had ties to the place and could not leave. The house ghosts who had sworn their loyalty to the castle and those who had died there, along with any who chose to stay. This left for a very empty castle. The Grey Lady hid away and was never seen, some suggested she was avoiding the Bloody Baron though none knew why. Nearly Headless Nick spent his time floating through the dusty old Gryffindor house table not responding to anyone. He had even stopped appealing to the Headless Hunt. The Fat Friar had turned one of the old classrooms into a chapel and never left, praying that some God, any god, would save the world from Voldemort's terror.
In the girl's bathroom on the second floor lived two ghosts, one that had been there since before Voldemort's first rise and one who came with his second and was very glad that it was no longer a girl's washroom. Ginny had passed on as she was not afraid of her death, but Harry, in his final moments was terrified, and so he was trapped. Forever in the castle that had you asked him a few years back he would have never wanted to leave and now would do anything to leave and do what he could to stop Voldemort. But he couldn't, he still hadn't even managed to leave the leave the bathroom. Apparently it took nearly a half a century to be able to move great distances from one's place of death. His first year was spent watching his the body of the basilisk he had stabbed as his last living action slowly decompose.
Eventually it was Myrtle that came to visit him realizing he might be lonely. She helped him get further and further away from where he had died until he eventually made it to the bathroom.