So the movie goes that Elsa is playing with Anna, but Elsa use her magic and hit Anna by acciedent. The king bings Anna to the trolls and they all help her.
Elsa freezes Arendelle, because people wants to kill her when she use her power accident.
So it's coronation day and Elsa use her power by accident and Elsa run away and freezes Arendelle. After that, Anna and Christoph wander and find Anna.
So on the way to Elsa, Anna and Christoph meet Olaf the snowman. When they reach the ice castle, Elsa use her magic and hit Anna by accident and Elsa create a gigantic snowman and it throw Christoph and Anna out the castle.
So Christoph bring Elsa to the trolls which the trolls raise Christoph when he was a child. The troll said he cannot help Anna, because it hits her heart and the way to fix it is true love. So Christoph bring Anna back to Arendelle for Prince Hans to kiss her, but Prince Hans betray her. So he capture Elsa and Anna walk in the snow and tries to find Elsa which Elsa break out of prison.
So its ends by Anna protect Elsa from Prince Hans and Anna turns into ice and Elsa bring her back by hugging her and Arendelle is in no more snow. Prince Hans was kick into the water and that is how Frozen ends.