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

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

Fatal error: require(): Failed opening required '//wp-blog-header.php' (include_path='.:/:/usr/local/php56/lib/pear') in /index.php on line 18