L.,
I will start by telling you this: In the words of my wonderful Grandmother, "If you want to know what your teenagers are doing, your going to have to snoop."
And what I mean by that is know where he is at every minute. He is still fourteen, so of course you have control over this. Be familiar with his friends and their parents. (I remember many times, some of friends' parents were bad influences and I was not allowed to go to their house...they could come to mine, but I did not go there.)
I would also try some family counseling. At this age, you can still make him go. He may not want to open up at first, but if he is comfortable enough with his counseler, he will eventually find that he might even like going. Tell him to think of it as a way to "tell mom and dad everything you don't like about them." That may light a spark in him! (Although it sounds harsh...but everything needs to come out!) You may find the root of the attitude problem. It could be anything from problems at school to depression. (Depression is so common at this age.)
I would also do this: Start a family dinner night. He must participate. Everyone must. Talk to one and other about your days. I know this will be "painful" for him at first, but hopefully he will come around. A counseler can help you. If he does not want to participate, simply say, okay, then you can't have video games or you can't have tv.
I must say, I also concur with Cheryl, in an earlier statement. Love and accountablity. They have to be accountable when you have to "adjust the attitude." But they also need your love more than ever now, even though they'd rather doing anything but show it! Take away video games, take away outings with friends, take away tv...just don't take away the hugs and love.
Last but not least, make sure it isn't drugs or alcohol. I know everyone says "not my child" but you never know. Better to be safe than sorry.
I hope this has helped. If you would like to talk more, please e-mail me. I just can't stress counseling enough.
Take care and God bless, Lee