Recently I adopted a 4 year old bull mastive. He's great except he does not listen to me. He was in a bad place before i got him. How can I get him to listen at such an age?
You really need to find out what motivates him. With some dogs it is toys and praise, but for the majority of dogs, special tasty bits of food can be used to lure a behaviour, or into a position, and also as a reward when he gets things right. Choose treats that you can easily carry in your pocket, like baked liver, or cubes of Edam cheese. It sounds as if you haven't had a great deal of experience with dogs, and a Bull Mastiff is perhaps not the easiest breed to start with. I think I might try looking for a dog training class nearby, where a gentle trainer might be able to give you some practical ideas. Just an afterthought. Has he has been checked to make sure that he isn't deaf?
Does he look at you when you talk to him or turn away from you when you speak, or does he completely ignore you?
I am having similar issues with my 8month old female rescue. She is starting to respond when I lower my voice and be stern with her.