If hypnosis didn't work for you, check this list:
1. You weren't born with hypnosis talent. Just like in music or math, some people have more potential. Sure, you can take lessons but you will always be limited by your lack of talent. Some people can't be hypnotized. You can't change that very much.
2. You don't believe in hypnosis. Now this is an area where it's possible for you to improve your faith by learning more about hypnosis. Maybe you think hypnosis is fake, or that people who believe in hypnosis are stupid.
3. You are fearful. If you say, I'm scared of hypnosis, maybe you could study a little about it. If you think that a hypnotist can take control of your mind, then you should learn more about hypnosis. Hypnosis is risky----well about as much as meditation. That's not much, right?
4. You didn't like the therapist. Maybe you could become better friends. Start over. Get to know each other. Or of course you could switch to a different practitioner.
5. You didn't really want to change your habit. If somebody else is pushing you, hypnosis won't work. Make your own decision to change.
That's a smart question. Here's the easy answer. Try hypnosis.