Website disappeared

Also from another thread I just answered:
So you will need to use FTP or Cpanel and delete that plugin from your site files on the server – find it here:

wp-content
   plugins
       wordpress-seo - DELETE THIS FILE

Ask your hosts how to access your files if you don’t know.

And for help with the problem with that plugin, go here:

https://wordpress.org/support/plugin/wordpress-seo