Father n law helped get us a vehicle, he ended up filling for bankruptcy a few years later, surrendered vehicle but was never repossessed. What to do?

The vehicle has sat in the driveway for 2 years after his bankruptcy went through. Should we try and register it, and drive it around since they have not repossessed it. Should we try and do a private lien sale on it since is abandoned on my property. Should I contact them and try to settle the debt, even though the loan wasnt in our name. I recently logged into that loan account online and showed next payment sept 20 2020, for $0. Still showed owing 20k on the loan tho. Its no longer on his credit since his bankruptcy finished 2 years ago.