You could have a story where a person keeps having nightmares that start to come true. Or a town where everyone disappears one by one under mysterious circumstances.
One idea could be a haunted house where strange noises and apparitions keep appearing. Another could be a forest with a mysterious figure lurking in the shadows.
A girl finds an old, mysterious diary in the attic of her new home. As she starts reading it, she discovers that it was written by a girl who lived in the house decades ago. The diary reveals that the girl was into some dark magic and made a deal with an evil entity. Now, as the current girl reads the diary, she starts experiencing strange events. Things in her room move on their own, and she has nightmares of the entity from the diary coming to get her.
One idea could be a story about an old, abandoned house at the end of a dark lane. A young girl, curious about the rumors surrounding it, decides to enter. Once inside, she hears strange whispers and feels cold hands on her shoulders, but when she turns around, there's no one there. As she explores further, she discovers a locked room with a faint red glow seeping from under the door.
A young woman moves into an old apartment. Every night, she hears a baby crying from the empty room next door. When she investigates, she finds a diary that reveals a tragic past of a mother and child in that apartment.
One scary idea could be a haunted house. A family moves into an old, dilapidated mansion that has a dark past. Strange noises start at night, like creaking floors and whispering voices. Shadows move on their own, and the family members start to feel like they're being watched all the time. Doors slam shut unexpectedly, and cold spots appear throughout the house. As they try to uncover the mystery, they find that the previous owners were involved in some sort of dark magic ritual that went wrong, and now the spirits are angry and want to drive the new family out.
You could write about a man who inherits an antique mirror from his deceased grandmother. When he hangs it in his bedroom, he notices that there are strange reflections in it at night. The reflection shows a different version of his room, with dark, shadowy figures moving around. As he stares into the mirror more often, he starts to feel a presence trying to reach out from the other side, and he realizes that the mirror might be a portal to a haunted dimension.
How about a small town that has been cursed? The townspeople start to transform into grotesque creatures at night. Their eyes turn yellow, and their teeth become long and sharp. The main character, a newcomer to the town, has to figure out how to break the curse before they too are transformed. Every night, they hide in their attic, listening to the howls and screams outside as the cursed townspeople roam the streets in search of victims.
How about a camping trip gone wrong in a forest rumored to be home to a vengeful spirit? The isolation and unknown can add to the scare factor.
One idea could be a story about a haunted mirror. A young girl moves into an old house and discovers a large, ornate mirror in the attic. Every time she looks into it, she sees a figure that gets closer and closer each day. Eventually, the figure steps out of the mirror.
A story about a cursed doll. A little girl finds an old, tattered doll in a thrift store. She takes it home, and strange things start to happen. Her toys start to move on their own, and she hears whispers at night. It's revealed that the doll was once owned by a witch, and now it's bringing bad luck to the girl's family.
One idea could be a haunted house. A family moves into an old, dilapidated mansion. Strange noises start at night, like creaking floorboards and whispering voices. They soon discover a dark secret about the previous owners, who were involved in a satanic ritual in the basement. Shadows start to move on their own, and things disappear only to reappear in a more menacing way.