Fatal error

Can someone please tell me what to do for the following error message for http://loveinourowntime.com/:

Warning: require(/home//public_html/wp-includes/class-http.php): failed to open stream: No such file or directory in /home//public_html/wp-settings.php on line 140

Fatal error: require(): Failed opening required ‘/home//public_html/wp-includes/class-http.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home//public_html/wp-settings.php on line 140

I don’t understand how this happened because the whole site was working fine two days ago and I haven’t made any page/post updates, haven’t added any new functionality or plugsins and haven’t made ANY changes.

I cannot tell what version of wordpress that I’m running because I cannot login. But it is an older version.

All help majorly appreciated.