Are you trying to login into your atlassian account ? You are posting here so I am sure you are in already. :p
Ask an admin to check your profile - RESET CAPTCHA if needed.
Ask an admin if you are a member of any group or not .
Lastly, ARE YOU SURE THAT YOUR ACCOUNT IS NOT LOCKED OUT ? :-)
Normally it occurs if the administrator try to play with the permissions, i.e; if the administrator take back your Software access you will not be able to login.
You can do the following to solve the issue:
1. Ask an admin to reset your password and provide you with a new password
2. Ask an admin if you rights to access the application and if not you cannot access, if you have the rights, a restart of server or re-indexing would solve the problem (after the setting a new password)