i need to enable mode rewrite in lighttpd it should no display the index.php extension ....
If I'm understanding your question, you need to rewrite /index to /index.php. This should do the trick.
server.modules += ("mod_rewrite")
url.rewrite-once = (
"^(.*)$" => "$1.php"
);
Note, this will also forward url's such as /image.jpg -> /image.jpg.php. If you need a more complex solution please adjust your question.