Ensure that caps lock is off, and that you are completely sure what your cPanel password is. If too many failed login attempts are made, you will be locked out of the system for 10 minutes. If you try to login during the 10 minute lockout period, the lockout will be extended.

If you cannot remember your cPanel password, it can be reset from the client area under Services > My Services > View Details > Change Password or by contacting technical or sales support.