I want to know Which one is sentence correct between "why does it do not good" and "why does it do no good"? I'm so confusing this.
Both the sentences are correct. Compare the following two examples.
I have no book.
<no, an adjective; qualifying book>
I have not a book.
<not, an adverb; modifying the verb, 'have'>
In these instances functionality becomes all the more obvious for article "a" as it does come between 'not' and 'book'.
Do remember the difference. It is never ambiguous. For better understanding, we would write the first sentence like this:
Why doesn't it do good?
It would be proper to take 'not' before the subject if the subject is a pronoun.