If you take your assessment and do not pass, you may be given the option to re-take your assessment.
If you have no more attempts, you will only see the below message:
In the case that you have no more chances, you will need to contact your site manager. If you do not know how to contact this person, click on Directory from the main page and search for the name of your department. Often you'll find a manager account with contact information.
If you cannot find or do not know who your manager is, you can contact technical support for help finding more information.