What we can use instead of "you" in professional letters. Please suggest me some words like "your good self" is good to use instead of you in letters. As we start letter "In reference to your letter no.". What I can use instead of you in such letters

Why?

You, your, you're are perfectly acceptable.

"your good self" makes no sense at all, not in English.

Maybe you should post your letter, then we can have a better idea of what you would like.

I don't know what you are looking for here. "in reference to your letter' is proper business etiquette.

Tick

Keep it simple. Use "you" not "your good self" or anything else. Keep your words plain, so that it is easy to understand and there will be no misunderstandings.