Codeigniter shared hosting 404 error

it is worked once if i changed .htaccess of root folder o the following

Code:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]

and changed in config.php

Code:

$config['index_page'] = '';

but only one request it worked fine and total site is hanged..even now home page or any static page is also not working.
 any body help