Sounds like you need to teach your dog who the boss of the house is. You need to go for obedience training. Find a class close to you and get signed up as soon as possible. Your local pet store should probably have a bulletin board with all sorts of training options.

What I did with my unrully dog was attach the leash to her collar and to my waist when I was at home. That way she had to be with me all the time and I could keep an eye on what she was doing. It worked well for us and she quit chewing the walls, furniture, etc.

Good luck, don't give up on him just yet, train him, he needs structure, boundries, etc, just like a child.