Error Message '404 Not Found' on my new post

I am having problem with my wordpress site. When I published and later navigate on it, it shows the url does not exist whereas it was not removed until after some few hours before the page comes up. I never for once put my site post on post delay. What do you think might have gone wrong and how to resolve it. Be informed that this problem is not applicable to all the post rather three of four out of the post per day.