"Unable to connect" is the message you get when typing in the wrong password. Too many unsuccessful login attempts with the wrong password temporarily bans the account.
Are you absolutely 100% sure you're entering the correct password? Uppercase versus lowercase letters, numbers, less than 16-characters in length, etc.? As a quick test, open Notepad on your computer and type out your password exactly as you would be entering it in the game's login screen. This helps ensure your Shift/Caps Lock and any buttons on your keyboard are all working correctly.
There have been a few threads where posters were insistent they were entering the correct password but upon further testing, discovered one of their keys was not working or it was misuse of Shift/Caps Lock.
If you've read the troubleshooting stickies in this forum and tried everything but still cannot login, you may have to send a private message to one of the administrators requesting a password reset for your account.
UPDATE: The new
password reset feature is now live. If you're still getting errors during login, try resetting the password using the e-mail address you registered your account with. Make sure it's less than 16 characters in length.