Can't access term.php file from wp-admin directory?

Question

When I open my domain www.bhajanbook.in/wp-admin/term.php it shows following error.

Forbidden
You don't have permission to access /wp-admin/term.php on this server.

Please note that I have already performed following task for debugging error.

• I have checked permissions for a file and which is 644. Its same like edit-tags.php. whereas edit-tags.php works fine.
• I also have checked ownership of file but its same for all files in wp-admin directory and which is bhajanbook:bhajanbook
• Please note that my hosting is vps and managed using virtual min
• I also have tried using deleting term.php and adding again from other wp site but no result.

• Also I have tried creating some other php file in wp-admin directory for echo simple message but same error.

• Below is my .htaccess file.

  <IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

Please help me.