When your VPS is installed by us with Kloxo or LXadmin the password will 'admin' and the username 'admin' too.
Note: if you reinstall yourself it will also be 'admin'.
If you still can't login then:
1) Login via SSH
2) cd /usr/local/lxlabs/kloxo/httpdocs
or
2) cd /usr/local/lxlabs/lxadmin/httpdocs
3) /usr/bin/lphp.exe  ../bin/common/resetpassword.php master NEWPASSWORD
Now try your password again.