Follow the steps listed in the following link to recover/reset the password. This would require rebooting the router.
http://www.cisco.com/en/US/products/hw/routers/ps274/products_password_recovery09186a0080094774.shtml
It appears Scott already post the link for you.
You may be able to log back in without having to do a password recovery if you have VTY lines configured with 'login' and 'enable password' instead of 'login local'. If you do have 'login' configured on VTY lines then you can telnet to the router using the password configured on the VTY lines and enable password to access the privilege exec prompt and set the username/password.
HTH
Sundar
