Blocked access to page 403 “Forbidden You don’t have permission

I have a problem with my website. I will describe in turn:

1. After installing the “All In One WP Security & Firewall” plugin, an error appeared with logging into the backend of the site.
2. I get error: 403 “Forbidden. You don’t have permission to access this resource.”
3. I disabled the plug via FTP.
4. I logged in correctly to the backend of the site and removed the plugin in wordpress.
5. I thought that the problem was solved, but the error 403 is still displayed …