Details migh be wrong as I’ve seen it long ago.
A movie about a man who accidentally stumbled upon a ghost who then asked the man for help with getting revenge on a rich guy. I remember that the movie had a bad ending: the MC was about to get killed(in his own house I think) the ghost intervened, and was forced to leave afterwards. I suppose he broke some rule that stated not to hurt mortals of whatever.
Details worth mentioning:
The ghosts in the movie were portrayed as regular people, the only difference being the fact that nobody can see them. NOT the cartoon style white floating thingy.
There was another ghost character. If I remember correctly, she was a young girl who killed herself by jumping off the stairs from the top floor of the apartment building she lived in.
My memory might be messing with me, but I think the movie had some sort of autumn vibe.