My account was JUST hacked! What do I do??

I had been playing got off for 20 minutes MAX and now everything is gone! My pets, clothes, sapphires, gems, anything worth anything is just gone! What am I supposed to do?? Can they review trading history? I don't take pictures of my things so how am I supposed to get anything back?? Ive spent so much time in this game since 2018 and now it's all just gone, I'm so upset and at a loss..