Does Narita express train N'EX from Narita airport stops at Shinagawa station in Tokyo If so how much will the cost of ticket from airport to Shinagawa station. Are all N'EX train stop shinagawa?

Yes, some of the Narita Express services stop at Shinagawa, not all of them. Some travel via Shinjuku. From Shinagawa to Narita, the ticket should cost about 2910 Yen. All Narita Express trains stop at Tokyo Station. If in a hurry, this is the best option.