[NEED URGENT HELP] All controllers showing 404 except default controller

try using index.php before adding your controller's name
build url in this format : domain name/index.php/controller'name/method in controller/parameters 
example : http://example.com/index.php/student/ 

PHP Code:

$route['default_controller'] = "home";

$route['(:any)'] = 'home/$1';    // http://example.com/any
$route['load/(:any)'] = 'home/load/$1';  // http://example.com/load/any

$route['student'] = 'student';  // http://example.com/student
$route['student/(:num)'] = 'student/profile/$1';  // http://example.com/student/1234

$route['admin'] = 'admin';  // http://example.com/admin
$route['admin/(:any)'] = 'admin/$1';  // http://example.com/admin/any 


My .htaccess code is here

Code:

RewriteEngine On
RewriteCond %{REQUEST_URI} ^system.*
RewriteCond $1 !^(index\.php|images|js|uploads|css|robots\.txt)
RewriteRule ^(.*)$ /index.php/$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]