The crowbar is an object found by Edward Carnby in Alone in the Dark: The New Nightmare.
The New Nightmare[]
The crowbar is located in the office of Obed Morton, it allows Carnby to open a trap door hidden in the ceiling of the floor of the Morton house so as to retrieve the office key and the key to the second floor. Then you can use it again to break through a wall, in the attic, in order to reach the hall where connects to Lucy Morton's room.