fatal erro function require site not opening

Fatal error: require() [function.require]: Failed opening required ‘D:\Hosting\11499599\html/wp-includes/class-wp.php’ (include_path=’.;C:\php\pear’) in D:\Hosting\11499599\html\wp-settings.php on line 66

I have this on my site. i tried updating to 3.6 then then fatal error shows up.to manually upgrade i deleted wp-admin wp-includes directory and now new ones are not uploading in wp-content is there.how to fix?? i dont want my web data to get erased