Thank you so much. No.6 did the trick by resetting .htaccess.
One more thing please. When I try to activate cornerstone, I get the following error:
Plugin could not be activated because it triggered a fatal error.
Fatal error: Cannot redeclare class Cornerstone_Plugin_Base in /home/name/public_html/wp-content/plugins/cornerstone/includes/utility/plugin-base.php on line 6
I tried to delete it, re-uploaded it manually once from the X-theme folder and another time from the pro folder. Neither worked and I still get the same error.
Can you please guide me on what I should do?
Thank you very much for your outstanding support.