Wordpress : getting 404 when accessing .php file inside any subdirectory

While editing the page from backend i got this error NetworkError: 404 Not Found - http://ift.tt/18tjUwi" any i am unable to run tinymce editor there due to this error

However files are there when i tried to run this file manually getting same error and it seems happening with .php file only while the .js files are running in same directory without any problem .

I checked the permissions of file even tried with 777 it works fine .

This is my .htacess

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]