Php link is not working

there is one project folder , which has sub folder.
sub folder has a php file. this php file display a link that opens index.php file,
but that dsnt work as in picture.
what is wrong with this , plz help

This does not appear to be a CakePHP project, and hence is completely off topic for this site. But try just using /index.php for your link instead of $_SERVER["DOCUMENT_ROOT"]. 'index.php'

thnks for your answer .