I cant login to my site

I cant seem to log in to my site on the screen is this
Warning: require(/home/ecova045/public_html/blog/wp-includes/class-json.php) [function.require]: failed to open stream: No such file or directory in /home/ecova045/public_html/blog/wp-content/plugins/admin-menu-editor/includes/shadow_plugin_framework.php on line 21

Fatal error: require() [function.require]: Failed opening required ‘/home/ecova045/public_html/blog/wp-includes/class-json.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/ecova045/public_html/blog/wp-content/plugins/admin-menu-editor/includes/shadow_plugin_framework.php on line 21