If you are getting an authentication error when trying to access your WHM, Console, webmail, or email from client software, and you are sure your password is correct, then odds are you are blacklisted. Here are some steps to Whitelist an IP. The first will be from the System Console via your Cpanel.
First log into the System Console: carvertown.com/how-to-access-the-system-console
From here you need to type in /scripts/cphulkdwhitelist your.ip.address
Now press enter.
Now your IP is whitelisted! You should be able to log into your WHM, webmail, etc with no issues. If you need to whitelist an IP in the future, you can use this method.