Вы потеряли книгу своего друга в парке, расскажите ему об этом и извинитесь

Hi Mark! I lost your book yesterday. I am so sorry. When i was in the park i met my friensd. I put the book on chair and went with my friend to cafe. After that there is not any book there. I will buy you a new one. Your friend, Sasha(например)