Dear Bob:
I have returned home from Canada now and I would like to extend my sincere thanks for your help in Canada. It has been one of my best vacations ever!
Back at home, however, I am surprised to find that I mistakenly brought one of your CD home with my luggage, the one which you lent me in summer vacation when I was preparing for a music course test. I am really sorry for this and I hope no bother has been caused because of my mistake. I decide to send it back to you as soon as possible, so would you please send me your current mail address so that the CD can successfully reach you soon?
I apologize again for my carelessness, and wish to meet you again soon!
Yours
Liming