Hades, God of underworld, took Persephone and brought her to his kingdom to be his wife, because she got forced to, or she would die.
Persephone's mother, god of agriculture, was super upset when she found out about her daughter being taken away, and now she won't let her plants grow and are dead.
Persephone is tired of being in the Underworld. All that is down there or is growing is such as apples and oranges.
Zeus lets Demeter have the plants grow because of the loss of her daughter and is happy to have the plants back growing again, adn if the plants grew back she demanded to have her daughter returned back to her.
Zeus and Demeter went into the Underworld and told Hades that Persophone needed to return, but Hades said every year I get to see her though because she ate half of the underworld fruit.
Until Persphone comes back from the Underworld, the underworld will be winter and when she comes back it will be springy outside for the half of the year.