Why wouldn't you have your passphrase written down? I've got mine written down at home and also in a safe deposit box.
Are you sure there is power to the ledger? (http://www.autoadmit.com/thread.php?thread_id=4019246&forum_id=7#36375343)
Also, try a new cord and a different computer(http://www.autoadmit.com/thread.php?thread_id=4019246&forum_id=7#36375369)