Brittany Nichole Collins was at her father's house in Nauvoo when she disappeared Sunday night.
Tammy Osborn said her daughter snuck out the window with her belongings some time between 6 and 7 p.m. Collins has not contacted family members or friends since Sunday.
"She hasn't been on Facebook. She won't answer her phone. None of her friends have talked to her," Osborn said.
A missing person's report has been filed with the Walker County Sheriff's Office.
Collins has black hair, blue eyes, is 5'5" tall and weighs 110 pounds. She was last seen wearing a white T-shirt, bathing suit, gold Walker Viking shorts and flip-flops.
Osborn said she does not know where Collins might be heading and is worried about her daughter's safety.
"I have no idea where she could be. She has no money and probably just one change of clothes,"Osborn said.
Anyone with information is asked to contact the Walker County Sheriff's Office at 384-7218.