Usually, when children are being disrespectful to parents there are at least one of three things happening:
1. They never were taught how to disagree with a parent in a respectful way.
It's so easy to overlook this point, because at the moment when our child is being disrespectful we tend to get caught up in our own feelings, "How dare he speak to me this way!... He has to learn that he can't be so rude..." Children should be allowed to disagree with a parent, but they way they do this has to be defined for them. So the next time your child contradicts you (and you shouldn't start this with a child under the age of 3), stop what you are doing, look the child in the eyes and say, "the next time you want to say "no" to me, this is how you can say it." Do this for a week or two. When the child does disagree in a respectful way, it's best at the beginning to compromise with him. Later on, you should at least acknowledge that he spoke appropriately.
2. The child doesn't feel that he can safely communicate his feelings to his parents. His abrasiveness may be a form of self-protection. He may feel that his feelings are never validated or that the parent is not truly listening to him. If this is the problem, then you will have to open up the lines of communication between you and your child, and you will have to rebuild trust. This can be done by consistently listening to your child and validating his feelings (even if you don't agree with them). And where appropriate, to compromise.
3. The child may not be connected to his feelings in the first place. If a child grew up with the sense that his feelings were being judged and not validated, then he may cut himself off from his emotional responses. Therefore, he could be upset about something, yet not even realize it. Though he is out of touch with the emotion, it doesn't mean that it will go away. It will come out in other areas including the way he responds to you. If this is the case, then the goal is to help the child get in touch with his feelings. One way to do this is to name the feeling for the child. For example, if a child responds rudely you can say, "I see that you are very upset now. When you have calmed down we can finish this conversation." Then walk away. If you do this enough times the child will begin to recognize where he is holding inside.