If a respective User's account has been disabled but you now want to reactivate/enable it again, follow these steps:
1. Go to the Configuration tab - to User Management.
2. Find the respective user (you can use a filter for searching by name or other parameters).
3. In the filter for “Enable” choose “-----” or “No,” which will allow you to see disabled users.
4. Once you have located the respective user, you should click on the edit button.
5. Then you will see the “Edit User” menu. Find the switcher at the bottom of the main page, then click on it, and then hit the Update button. Now your user will be enabled/reactivated.