Can not access email thru Outlook


New Email
I use outlook to access my yahoo email account. Today I have started receiving the following error message:
Task ' - Receiving' reported error (0x800CCC92) : 'Your e-mail server rejected your login. Verify your user name and password in your account properties. Under Tools, click E-mail accounts. The server responded: -ERR [AUTH] invalid user/password'
The network password screen keeps coming up and highlighting password-I have not changed the pw and am typing correctly.
Sometimes the server says - othertimes it says I think the pop is for incoming messages and smtp is for outgoing. I am not able to receive or send messages. I have rebooted computer - reset att mode. Can you help me?