yeah if you don't have the tracking number off the receipt going to be hard...
you can call your post office and maybe the supervisor can look around the office for you...but this almost asking for a small miracle...haha
I worked in a small office in Calif...so if the supervisors were not busy they might help you...but if your PO is a large office...forget it..try get the numbers again from Luis
good luck Bruddah!