I Don't Want to Be Friends with You Episode 1

Sick of her seemingly neglectful mother Li Qing Tong's thoughtless actions and outright refusal to reveal the truth about her personal life, 17-year-old Li Jin Bu leaves home to stay overnight at a Public Bathhouse. However, she opens a door and finds herself in the Men's Public bath of Tieyuan, her mother's hometown, stuck in the year 1999. She receives help through a mysterious phone call and stays at a hotel, running into Duan Xiao, a boy she had seen earlier at the Public Bath. He agrees to help her during her stay. Li Jin Bu sets out to find her mother and finally finds her as a young 17-year-old girl who does not recognize her. (Source: iamconqueror at MyDramaList)