Hi Uma,
The password is admin and the username is admin
Have you run any other sandboxes on your machine as you may want to use a non-cached browser session.
You can always revert to bridged networking which will take an IP address from your network. However, you will need to log into the Sandbox by using the virtualbox session to find the IP address. Then you can use this IP address to connect to the machine instead of your loopback address.
Thanks
Dave