Fatal Errors after deleting WP-Super-Cache

Hi,
I’m running a network site & yesterday I inactivated, then deleted WP Super Cache. Now I cant log in at all & an error message is showing. Yesterday the error was: Fatal error: Call to undefined function wp() in /home/cal65/public_html/wp-blog-header.php on line 14
today it says: Fatal error: Call to undefined function force_ssl_admin() in /home/cal65/public_html/wp-login.php on line 15

Also both days there is extra code showing which you can see at my site address: [Link Moderated for user security purposes] I don’t know why the error message changed as I haven’t changed anything since. Could someone please help me fix this. Do I need to upload WP-Super-Cache in the backend to get it all working again or to do a complete reinstall of the entire domain? I do have all the sites backed-up, but am wondering if there is an easier option as I’m not super techie. Thank you, Cal