I saw this once on DogWhisperer, what he did is was to take the dog down the street (he either carried it or drove it there, can't recall now) and THEN, put it on a whole other brand-new leash that the dog had never seen yet, the dog happily wore the new leash to return to it's home. Walked nicely, no dragging involved...The D.W. said the old leash already had too many bad experiences assosicated with it, so he got a whole brand new one for the dog.
This helped the dog like walking on the leash. Wearing the leash to return home...(i suppose then, after having positive experience wearing leash to return home, the dog must've eventually accepted that new leash and could then walk out of the house in the leash, can't remember, but they did go back and show the owners all happy they could now walk their dog.....)