dear sir : I bought iphone x and its kind from the United States from ( wall mart ) and when I started operating I discovered that it was locked on one mobile phone network and that it does not support networks in my country please send me the solu

You bought the wrong phone. If you knew you would be using the phone outside the US, you should have bought an unlocked phone from Apple. Or better yet, since iPhone does not come with International warranty, you should have purchased your phone in your home country.

If you are past the return date for the phone from Walmart, sell it to someone you know in the US. If you are within the return date either come back to the US or send it someone in the US who can return it for you.

This is not Apple, it’s a User forum, even so, it’s normal to discuss issues with whom you purchased the product from, namely Wall Mart.

You need to contact them and see what they are prepared to do, but if you didn’t specify an unlocked version I’m not sure how things will end up.