In the country of the blind what is the main reason that the people of the valley do not believe nunez when he tries to explain the world of sighted humans?

Because they refused to think that an outside world existed that can help them, as they have lost the sense of their sight since fourteen generations.

Explanation:

"The Country of the Blind" is a short story penned by H. G. Wells. The story is about a man named Nunez, a one-eyed man, who finds a 'country of the blind' at the far sight of the mountain.

When Nunez tries to explain to the people of the 'country of the blind' about an outside, they do not believed him. The 'country of the blind' has been separated by the outside world after an earthquake struck the valley reshaping the mountain that completely cut off the valley from the outside world. All the people of the valley are born blind since then in the 'country of the blind.'

Since fourteen generations the people of the valley lived their which slowly adapted them to think that even if there is an outside world. So, they refused to think that there can be an outside world to help them.