Who much trouble am I in?

I dont understand why I received this in the mail. I don't think I did anything wrong. Do I move forward with a lawyer to talk to these people? Can anyone please give me so insight? Thank you in advance.

I dont understand why I received this in the mail. I don't think I did anything wrong. Do I move forward with a lawyer to talk to these people? Can anyone please give me so insight? Thank you in advance.