The most common problem when your password is rejected, or being unable to log-in is:
- you are using the wrong password
- you are using a password with invalid characters or characters the FTP server doesn't understand
- you are using the incorrect username
- you are connecting to the wrong FTP server
In all cases you should double-check that your settings are correct, and for point 1 and 2 you can change your password in the control panel to a different password using only lower-case characters, upper-case characters, and numbers to see if that fixes the problem.