ContactManager contactManager = Factory.CreateObject("tracking/contactManager", true) as ContactManager;
    
Contact contact = contactManager.LoadContactReadOnly(userName);
return contact;

This method doesn't require initialization of the tracker, which is handy if the state should be changed outside of the site context (for example in the shell).

var stateManager = AutomationStateManager.Create(contact);
automationStateManager.MoveToEngagementState(stateItem.ParentID, stateId);
stateManager.SaveChanges(AutomationManager.Provider);

 AutomationMetadataProvider automationMetadataProvider = Assert.ResultNotNull(Factory.CreateObject("automation/metadataProvider", true) as AutomationMetadataProvider);            
 var context = AutomationManager.Provider.GetAutomationContext(ID.Parse(contact.ContactId));            
 context.Enroll(fromStateItem.ParentID, ID.Parse(fromState), automationMetadataProvider.CalculateWakeUpDateTime(ID.Parse(fromState), DateTime.UtcNow), null);
 AutomationManager.Provider.SaveAutomationContext(context);