Well, that's a mystery.
Your account is a 4 year old guest account, and guest accounts can't do a lot -- including not being able to add much to your family tree here. (the policy on becoming a full member has changed recently, but your old guest account might be stuck under the old policy).
Are you sure it wasn't another site where you uploaded your tree? There doesn't appear to be any evidence that it was ever here.
Best thing to do, is to contact the admins: firstname.lastname@example.org and provide as much detail as you can.