There may be times when you need to reactivate a user that was previously deactivated.  This is easy to do, simply edit the user record and check the Active field.  This assumes that you have an available user license.  If you do not then you will need to either deactivate a user or order a new license.

Once a user has been reactivated, you can send them a reset password email if needed (their prior password should still work).

Finally, if the user should appear as a resource in the calendar you will need to make their corresponding staff member record active as well since reactivating a user does not change the status of their staff member record.

To do this go to the Staff Members tab.  If you do not have a tab setup, go to the + symbol



View All staff members and click Go



Click on the user name, edit their profile, and click the Active check box 

Don't forget to Save!