No answers a yes/no question.
"No, the president wasn't surprised by the results of the election."
No precedes a noun that has no article.
The company had no worthy rivals in the industry.
No can be used before a noun that is preceded by an adjective, as in the preceding example, but it is not used before any, much, many, or enough.
Jim has no argument with which to continue the discussion.
The manager had no reason to support his request for a raise.
Not precedes a noun that has an article.
The virus is not the source of the outbreak.
Not precedes any, much, many, or enough.
Not many amateur astronomers can afford the equipment necessary to study the nova.
There is not much budget left for another trial.
Not makes a verb negative.
They do not want to proceed with the experimental study.