I've seen that there are a few formatting option for comment. In some comment I tried to write a few words in a new line but that I could not add new line in comment. I can understand that comment tools may not be as rich as reply tools but I think sometimes it is necessary to add these options in comment. Where can I get the formatting option for comment? And is there any new line option for comment?
And is there any new line option for comment?
No, and I don't think there should be.
Comments are made to be short, asking for clarification or link to another page. You can make your comment "rich" by surrounding variables and methods with "`", exactly as you do in answers.
If you feel the need to have a new line, you might want to consider answering the question1 instead of commenting on it.
1 Really consider it :)