Don't file an item not received claim or freak out to much yet. Why don't you contact the seller and ask what address they shipped it to. It is possible they sent you the wrong tracking number, that USPS tracking is incorrect, or USPS made a mistake and maybe between you and the seller you can have USPS correct it. Definitely give the seller the benefit of the doubt right now and see what you can both do to make sure you get your package.
Worst case situation, the wrong address was written down and you will be protected by Paypal or if USPS delivered to the wrong country, you will still probably be covered by Paypal and the seller will be covered by USPS insurance.