大致可以这样说;
Dear ****,
There are a lot of things you chould do. You could talk about the problem with your parents, and tell them you felt sad when they argued with each other. Then you could do more chors to help your mother or study hard to make your parents happy . Or may be you could tell jokes to make them laugh or ask them to communicate with each other better.
Don't worry, everything will be fine!
Good luck!
Yours,
name
(英语课本上有很多句子可以现成用的,希望这篇文章对您有帮助!)