thanks for replying. I got the issue.
I changed define('HOMEPAGE_MY', 2); to define('HOMEPAGE_MY', 1);in lib->moodlelib.php.(As I noticed in core file). Now dashboard option is visible.
But again one problem raised. It is not redirecting to dashboard page although i set in navigation. It is redirecting to index page. If you have any solution please let me know.
Thanks a ton.