How Can I Write A Nice Letter To Someone Who I Have Never Met, Without Being Rude,intrusive Or Threatening.

The content of the letter would depend on the reason why you are writing it to someone you have never met. It should be simple to write a nice letter to almost anyone.

I would start the letter with a Dear . . . give the person' s name.

Give an honest reason for writing the letter.

If you are expecting a response then nicely suggest that he or she write back to you, or even give your phone number or other contact.

Simply close the letter with something like "Looking forward to hearing from you. . . .then your name.

Begin the letter with a nice greeting, introduce yourself and then explain the reason why you have written the letter.

An already written letter to a girl you never met

Well its not that hard this is what you do you start  by telling a bit about your self and then the words will just start coming to you as you are write ...