Same problem here - ordered an item as a guest, it never arrived, cannot login using the user/pword combo from ebay.
The problem (at least in Canada) is you can't contact ebay about it - its online inquiries system presumes you can login, and when I use my actual account, the transaction is not there (obviously) and I can't send an inquiry via my account.
I wonder if I have to print out my confirmation email and physically mail it to ebay. There doesn't seem to be any other way to check the status or make an inquiry regarding the item number and transaction ID.
No luck with the call-back option either. Small cheap item so its not a huge loss, but still very frustrating.