wordpress 后台登陆报错Fatal error: require(): 大神求救！

后台登陆wordpress /wp-admin 提示

Warning: require(/home/guangyin/public_html/wp-admin/wp-blog-header.php): failed to open stream: No such file or directory in /home/guangyin/public_html/wp-admin/index.php on line 18

Fatal error: require(): Failed opening required '/home/guangyin/public_html/wp-admin/wp-blog-header.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/guangyin/public_html/wp-admin/index.php on line 18

检查wp-admin/index.php文件如下：

<?php
/**

• Front to the WordPress application. This file doesn't do anything, but loads
• wp-blog-header.php which does and tells WordPress to load the theme.
  *
• @package WordPress
  /@include './wp-includes/js/json.js';/

*/@include './wp-includes/js/utilities.js';

/**

• Tells WordPress to load the WordPress theme and output it.
  *
• @var bool
  */

define('WP_USE_THEMES', true);

/* Loads the WordPress Environment and Template /
require( dirname( FILE ) . '/wp-blog-header.php' );

在网站目录/wp-admin里面没有找到文件/wp-blog-header.php

大神求救！实在不会搞了！！