If you are entering correct username and password and still you are not able to signing to your yahoo mail account there can be a problem with your browser which needs to be fixed. Users must ensure to download the latest portion of the browser whenever there is an update available. Old browser version may fail to work properly and yahoo mail may not be compatible with such old versions and may not function properly. It is advisable to try log in to yahoo mail account from a different browser. If you are able to log into your yahoo mail account from a different browser you can be sure that the problem is with the browser you were using and not let your yahoo mail account. Call the Yahoo technical support to learn more.