Why does your dog not listen to you? The simple answer is: Because he thinks he doesn't have to. Did you inadvertently train your dog to ignore your commands and not listen to you?
How can you turn this around and train your dog to listen to you? Leadership is the key. Your dog must believe that you are the leader and the dominant one in your relationship. This concept is much easier to teach when the dog is still a puppy, but you can train your dog regardless of age.
First of all, dogs believe that they live in a pack. To the dog this means that no members of the pack are equal. There is a leader who is the dominant member, and then a "chain of command," going from the next most dominant member all the way down to the least dominant member. If the leadership role is not taken by a human member of the pack, the dog will take the leadership role.
Here are some ways to become the leader in the dog's eyes:
When taking your dog for a walk, never let your dog pull the leash and walk in front of you leading the way. Also when you and your dog approach a doorway, you should go through the doorway first before your dog. In your dog's mind, the leader or dominant one is the one who leads the way.
Playing tug of war with a tug toy can be a fun game. But when the game is over, you must be the winner. Do not just drop the toy and walk away. Your dog will think that he has won because he is the leader. Instead, train your dog to drop the tug toy into your hand, signifying that you, as the leader, have won the game.
When reuniting with your dog, do so in a calm, controlling manner, reinforcing your leadership role. Do not allow your dog to jump up on you. Bend down to your dog's level to quietly greet your dog.
Only allow your dog on your bed or other furniture when he is invited to do so by you. For example, at bedtime you should get into bed first and get comfortable. Then allow your dog to jump up on the bed. In this way, you as the leader have taken the choice area of the bed and have decided to allow your dog join you.
Train your dog to obey obedience commands. This is very important. When giving your dog a command, say the command only once. For example, say "Sit". Do not say "Sit, Sit, Sit, I said Sit, You Better Sit" etc, over and over again. You want your dog to comply on the first command. If your dog does not, you must enforce your command. In this case, gently push your dog into the sit position and praise your dog. (This is actually a very over-simplified explanation of obedience training. See my articles, "How To teach Your Dog To Come When Called" and "Training The Submissive Dog" and watch for my future articles on the subject of dog obedience training.)
Most importantly, have patience. If your dog has spent his entire life not listening to you, it may take some time to train your dog and make him believe that you are the leader. But it will be worth the time it takes. Dogs are generally happier when they have a strong benevolent leader and you, as the dog's owner, will be happier too.