How do you get Proof that your car was repoed?

Two ways:

1). You will receive a notice from the repossessing agency notifying you.
2). You can call the local police to report it stolen, at which time they will notify you that it was repossessed.

In either event, you will undoubtedly be aware that repossession is the most likely scenario, considering you hadn't made a payment for an expended period on the vehicle note, and you had received contact from the lender advising you that repossession was the next likely avenue due to your noncooperation.