Follow the steps below to reactivate a department.
Select Appointments > Configuration… > Departments.
Place a check in the "Include inactive departments" box.
Use the Show All button to view all departments or use the Search Bar to further drill down your search.
Select the department from the list.
Click OK when the pop-up displays.
Uncheck the Make this department inactive checkbox.
Once a department is re-activate,d the resource(s) that were previously associated with it will no longer be associated. You must associate resources with the department again.