I’m trying to remember the name of a book I read a long time ago. I don’t remember much. I do remember the main character wakes up in a darkened area, possibly a city. He has no memory.Then there is something about a mirror? And I can’t remember for sure but I think there are creatures that are either hunting him or that he ends up finding. I know it’s not much to go on. I think I remember something about a car or a bus, maybe it’s a focal point or where he woke up? Any help would be great.
the main character wakes up in a darkened area
He lives alone in a dark castle in an endless forest.
He has no memory.
This also checks out, he has no clear memory how he got there or even how long he has been there.
I think there are creatures that are either hunting him or that he ends up finding.
Later the main character finds another castle where he finds other people, but those are normal humans. He does see a horrible creature in the castle, this comes back in the last point:
Then there is something about a mirror?
The story ends with the reveal that the creature he saw was just his own reflection in a mirror.
What doesn't fit with your description is that it's just a short story, not a full book, there is obviously no mention of cars or busses, it's not set in a city and no one hunts him.