Dear Ms (фамилия учителя),
I'm really sorry for troubling (беспокойство). But I wasn't at school yesterday, because I was at the hospital and I'm still sick. And I want to tell, that I won't visit lessons tomorrow.
Could you give me my homework, please? I promise, that I will do it all.
I wish, I get well soon! Thanks for understanding and sorry again.
Yours sincerely, (твое имя)
Сорян, что долго - отходила...