Delted music off data

[LoganHelps]

Hey everyone, I have a weird problem of my Kyocera Duraforce Pro on android marshmellow. Basicly I download music on data, or wifi sometimes, and I go to offline mode because theres no data at school and the wifi blocks downloading music. I go to listen to music after a class, and my playlist reverts to old songs i had. I could try to make a new playlist, is there any other ideas though?