Who owns the horse?

Ok, my friend has sold a horse, and now the buyer has stopped making payments.

The horse is with the buyer, as it was allowed to go to their place once a dposit was made (wich was done).

A contract was made by the buyer, wich was sentto my friend and was signed by the buyer.

It stated the due date on wich the horse was to be paid off by, wich has now passed.

There is no address of where the horse is, or contact details of the purchaser. There is also no mention of what was to happen if the horse wasnt paid in total.

Also my friend didnt send them (wich was impossible anyway) a copy that was signed by himself.

Does he have a leg to stand on to recoup costs and or the horse?

Thanks.