hi! how can i solve this error on server

[jam]

all need fine on FTP i already uplods it..

but always ive incounters this problem..

Not Found

The requested URL /index.php was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Apache/2.0.63 (Unix) mod_ssl/2.0.63 OpenSSL/0.9.8b mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 PHP/5.2.5 Server at Index of / Port 80

how can i solve it?..thanks