Her mother Demeter-goddess of agriculture- found out and roamed the Earth unable to find her. After taking to Hecate and Helios, she found out about the event and in grief, made the land infertile. Zeus then sent Hermes to retrieve the lost goddess and Hades agreed. He tricked the hungry goddess into eating a sacred seed- which would make her return every six months. Demeter and her daughter were reunited, yet she found out about the event and was saddened that she'd lose her daughter for six months.
This is why we have the seasons. In the spring and summer, the two are united and so in happiness, Demeter lets plants grow. However in the fall and winter, the grieving goddess makes the earth barren and infertile, because she doesn't have her daughter. Its also why we celebrate the two equionix rituals.