When your VPS is installed by us with lxadmin the password will be the same as what you asked for on setup.
If not try "admin"
Note: if you reinstall yourself it will also be "admin"
If you still can't login:
Login via SSH
cd /usr/local/lxlabs/lxadmin/httpdocs
/usr/bin/lphp.exe ../bin/common/resetpassword.php master
Now try your password again.
If you still can't get it to work, create a support ticket.