If you have lost the administrative password of your Zen Cart application and the password reset link is not working, you can directly reset the password in the database of your application.
In order to do this, log in to your cPanel and open the phpMyAdmin tool in it. Then select your Zen Cart database and open the zen_admin table (note that the table prefix may be different). Then click the Browse button.
On the next page, click on the little pen icon to edit the record for your administrator username. In the "admin_pass" field enter the following string:
This will reset the administrative password of your application to admin. You can now log in and change the password to a different, more secure one.