John,
Without seeing all the paperwork involved it is difficult for me to say what has occurred.
Are you saying you bought a truck and signed no paperwork for it, drove it away, it has financing on it, again nothing signed, and the bank or lender repossessed it?
If you are wanting to argue the validity of a contract you will need to consult an attorney for this.
As for getting the truck back, the laws do vary according to area and also what type of lien, security contract or financing is on the vehicle, but usually to redeem a repossessed vehicle you would need to pay all the past due payments and possibly any fees incurred by an agent in repossessing the vehicle.
The finance company or bank should be able to give you an exact figure as to how much to get the truck back.
In some areas if this is the second time they have repossessed the vehicle, the lender does not have to allow you the opportunity to get the vehicle back.
Let me know how this works out for you.
Jon