018: My Trailhead account has expired "for lack of activity." How do I get it re-enabled?
For security reasons, Trailhead accounts that have not been accessed for more than 365 days are automatically disabled. If you need your Trailhead account re-enabled, please submit a support request via the Mines Help Center (http://helpdesk.mines.edu/).
If your account has been locked out for lack of use, the error message you receive will state: "Account Disabled: This account has expired for lack of activity. Please contact your system administrator regarding the status of your account."