# nano /etc/nginx/nginx.conf

Locate your domain (example.com) virtual hosting configuration and before “location ~ \.php$ {” add following lines:

if (!-e $request_filename) {
  rewrite  ^(.*)$  /index.php?q=$1  last;
  break;
}

At the end your configuration should look as follows:

server {
    server_name     example.com;
    index           index.php;
    root            /var/www/example.com;

    if (!-e $request_filename) {
      rewrite  ^(.*)$  /index.php?q=$1  last;
      break;
    }  

    location ~ .php$ {
       fastcgi_pass  localhost:9999;
       fastcgi_index index.php;
       fastcgi_param SCRIPT_NAME $fastcgi_script_name;
       fastcgi_param REQUEST_URI $request_uri;
       fastcgi_param DOCUMENT_URI $document_uri;
       fastcgi_param DOCUMENT_ROOT $document_root;
       fastcgi_param REMOTE_ADDR $remote_addr;
       fastcgi_param REMOTE_PORT $remote_port;
       fastcgi_param SERVER_ADDR $server_addr;
       fastcgi_param SERVER_PORT $server_port;
       fastcgi_param SERVER_NAME $server_name;
       fastcgi_param SCRIPT_FILENAME  /var/www/example.com$fastcgi_script_name;
       fastcgi_param QUERY_STRING $query_string;
       fastcgi_param REQUEST_METHOD $request_method;
       fastcgi_param CONTENT_TYPE $content_type;
       fastcgi_param CONTENT_LENGTH $content_length;
    }
}

Save and close the file. Restart nginx:

# /etc/init.d/nginx restart