Custom wp-admin login URL not found

I apologize if this question has been answered elsewhere, but I’ve spent awhile perusing the boards to no avail.

Since my last WordPress update, I have been unable to login to my dashboard using my custom wp admin URL. I changed my login URL using a plugin – Better WP Security, I believe (though I can’t login to confirm the name of the plugin!) I receive the following error when I try to access the site:

http://www.tanya-roberts.com/wp-login.php?oymqzdk46l2hvj4zg0dj0
“Page Not Found – The page you’re looking for doesn’t exist”

I have access to phpMyAdmin via DreamHost but I’m still very new to this and don’t know where or what to look at. Your help would be greatly appreciated.