My mail in my iPhone 4S is not working.

My mail is not working with yahoo. It keeps saying the connection to the server is failing. I tried adding a new account but it is not working. It keeps saying that the password and username is incorrect. What should I do??? Is there anything that I can do?? It is has the IOS 7.1.2 update. I tried updating it to the IOS 8 but it does not show anymore updates, just to see if that is the problem.

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That doesn't sound like a problem with your phone. How long has it been happening? Are you sure your connected to the internet?

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