As a teacher, I have always been amazed at kids who have their work done but don't turn it in. An entire room of kids turning in work, but one of them doesn't notice the commotion that entails. Still baffles me.
Having just reread you Q, I wonder if he is refusing to turn in HW, or is he refusing to complete his HW in the first place. It's probably that. I've heard of parents successfully getting their children to be required to attend detention (after school and/or Saturday) so that their HW gets finished.
I am also AMAZED that an AP class doesn't require homework!!! Usually an
AP class requires double the homework, with extra requirements on both reading and writing. Wow! I'd talk to the teacher about that one to see whether that is true. Perhaps he has a source for getting HW completed for him in that class.
To the issue at hand, I'd double up on some posters' advice already given: look into depression; keep working at having a conversation with him so that you can be his confidant, rather than moving towards punishment for the sake of punishment; remember that the teenage years are a time they are starting to separate from parents, and some do not go through the process in a way that is safe and useful to themselves; work to find a male role model who lives in the vicinity, perhaps his church youth leader; get him into counseling, if he will allow it, which tends to be less likely when boys are involved.
It may be hard to establish new norms for the house, such as no electronics in your room, no cell phone, et al. For me, based on what I've heard from parents, I will be establishing no cell phone in the room after I go to sleep and no TV/games in the room (I'm going to try no games at all. My kid is five, and I'm still working out the details). Remember, with X-box, cell phones and the internet, your child is leaving the house even while he is physically in your home.
I would also establish that the parent needs to know where the child is at all times. I've heard of parents requiring a check-in phone call from the phone of parents with whom a teen spends the night.
I've also heard of parents taking and picking up their children for all out-of-the-home events. Would not allow other children/teens drive their child anywhere. That way, you know where the kid is, you know when the kids is returning home, and you know whether or not the driver has been drinking. You also know who the other kids at the event are, and you can observe whether the activity is appropriate or not.
In addition, I would establish what is an appropriate tone of voice when communicating with others, especially family members. Be sure to show it to him as well as expect it from him.
Perhaps consult the Jim Fey "Love and Logic" website for advice. Allow for natural consequences.
Get his school counselor involved. Make sure the counselor has you son on his or her radar as caseloads are high. See whether there is a career search done in any particular class, see what resources the school offers on the issue, and see whether it is on record that your child has named any particular major or career choice of interest. Try to hook him by discussing the future (which may be what he is avoiding--going into today's job market is scary.)
See whether there is a school staff member who can act as a role model.
Find out who he is spending his time with and meet the parents, if you haven't already. See whether those parents are having the same issues.
I just had a great thought--the solution is very Jim Fey-like. I think I might approach it as, "You will be spending more time around the house while I investigate what is happening. It may take me some time. What can you help me with?" Provide him with a list of "To Do's" you have in the "investigation" into how to get him back on track. Those things are all the ideas above: visit counselor, visit youth minister, talk to other parents, etc. Make a list, and estimate how much time it will take to carry out all of these items. Ask what he could do to help you with those "To Do's" so that the process could be shorter and he will be able to regain some time to himself after the process is over. After all, why should it only be your time that gets eaten away while the problem needs to be solved?
You also mention that you've just gone back to work. This may be his way of saying that he still needs your attention.
Hang in there.