Site stopped working after update: failed to open stream:

My site stopped working after I updated it.

I get this warning.

Please help make ?? a ??

My website is https://www.joujoumylove.com

Warning: require(/home/shopjack/public_html/joujoumylove/wp-includes/session.php) [function.require]: failed to open stream: No such file or directory in /home/shopjack/public_html/joujoumylove/wp-settings.php on line 122

Fatal error: require() [function.require]: Failed opening required ‘/home/shopjack/public_html/joujoumylove/wp-includes/session.php’ (include_path=’.:/opt/php52/lib/php’) in /home/shopjack/public_html/joujoumylove/wp-settings.php on line 122