I am not able to use closed states. What might be the reason?

Before working with closed states, you must ensure that the Closed States module is enabled. Only CRM admins can enable or disable modules. 
Follow these steps to enable closed states:

1. Log in to your CRM account.
2. Click the User Menu on the top right corner of the CRM screen.
3. Click Settings.
4. Select Modules under Module Management.
5. Look for Closed States under the modules list.
6. Enable the checkbox beside Closed States.

To learn more about closed states, click here.