Unable to reactivate cancelled MobileMe trial account
That account shouldn't be burned since Apple explicitly allows for renewal of expired trials as part of the normal upgrade process. You will very likely lose your data if it has been expired past 15 days but you shouldn't lose the account if you still know the password and can answer security questions or account history questions if you get to a human for support.

The system is in the middle of a change where they are phasing out physical box with activation codes and moving to all online activations.

If you can't renew it following this link then hop on the Express Lane and ask for help with Mobile Me billing. You should get connected to someone that can look up your account and see why it might be blocked.

I have had success adding these accounts as a sub-account on a family pack as well, but that involves more money or finding a friend to "resuscitate" your account long enough to renew it as a stand-alone account.