Enable debug mode and reproduce your last action in order to see the actual error in the browser, then copy it here so we could assist you. 

thanks for reply , ross

please chick this
http://www.mashaheir.com/index/index

paste ur htaccess file here or try put original one in and see if still problem

What did you do before that started to occur?

htaccess



# For security reasons, Option followsymlinks cannot be overridden.
#Options +FollowSymLinks
Options +SymLinksIfOwnerMatch
RewriteEngine On

AddEncoding gzip .gz
AddEncoding gzip .gzip
<FilesMatch "\.(js.gz|js.gzip)$">
  ForceType text/javascript
</FilesMatch>
<FilesMatch "\.(css.gz|css.gzip)$">
  ForceType text/css
</FilesMatch>


RewriteCond %{REQUEST_URI} !^/index\.php
RewriteCond %{REQUEST_URI} !/ow_updates/index\.php
RewriteCond %{REQUEST_URI} !/ow_updates/
RewriteCond %{REQUEST_URI} !/ow_cron/run\.php
RewriteCond %{REQUEST_URI} !/e500\.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.xml|\.feed|robots\.txt|\.raw|/[^.]*)$  [NC]
RewriteRule (.*) index.php

It differs from the default htaccess:

replace it with this code:

Options +FollowSymLinks
RewriteEngine On
 
AddEncoding gzip .gz
AddEncoding gzip .gzip
<FilesMatch "\.(js.gz|js.gzip)$">
  ForceType text/javascript
</FilesMatch>
<FilesMatch "\.(css.gz|css.gzip)$">
  ForceType text/css
</FilesMatch>
 
 
RewriteCond %{REQUEST_URI} !^/index\.php
RewriteCond %{REQUEST_URI} !/ow_updates/index\.php
RewriteCond %{REQUEST_URI} !/ow_updates/
RewriteCond %{REQUEST_URI} !/ow_cron/run\.php
RewriteCond %{REQUEST_URI} !/e500\.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.xml|\.feed|robots\.txt|\.raw|/[^.]*)$  [NC]
RewriteRule (.*) index.php

seems like your server does not meet our requirements.

replaced it
the same problem

Anas, I will need access to your Cpanel, please PM me, I'll take a look at the issue.