Question

write a letter of thanks to a stranger for sending back your bag containing some important paper or documents

Answer 1

Dear stranger,
I am very thankful to you for sending back my bag containing some important paper  or document.

Answer 2

(senders address)

(date)

Respected Sir,

                       I don't know you personally but I want to thank you for returning my bag.

                             Well I was carrying some important documents in my bag but unfortunately due to work pressure i forgot to take my bag while getting off the metro but luckily you found my Id card in my bag and so finally I got it back.

                        I want to thank you once again and you have been an examples for the rest of the citizens.

Your's lovingly,

Subhendu.