1. Shutdown the ArcGIS Server process2. In a Web Browser open the ArcGIS Server help. Navigate to the topic Administering ArcGIS for Server > Securing your ArcGIS Server Site > Configuring ArcGIS Server to be secure > Managing users and roles > Resetting a forgotten password.3. Following the instructions in the "Resetting the primary site administrator's password" section, change the password for the primary site administrator back to the previous value.4. Start ArcGIS Server.