I have lost my diploma certificate,I have already report to the police station,so I want to get another certificate from the college,how am I going to write that letter?
Well, the easiest way would be to go on UsingEnglish.com, and post a question like that and then someone will write it for you. You don't even have to register! Very simple.
If you give the addres, maybe they'll even put a stamp on it for you!