I have recently been experiencing some sleep resistance from my 24-month-old daughter, so I know how frustrating it can be. I agree with the mom who posted that 9 or 10:00 p.m. is a little late for bedtime and that kids who don't get enough sleep tend to not want to sleep; it is paradoxical but true. So, I would try to get your son to bed earlier by about 15 minutes a night until you have backed him off to around 7:45 or 8:00 p.m., if that is feasible for you and your family. As the other moms stated, a bedtime routine of bath and a few stories may help as well. Also, we find that our daughter responds well to being given a ten minute warning prior to ending play. We then clean up toys together and head upstairs for the bath and stories.
During the day, which is when we have experienced the most struggle, I have found that routine is still the way to go. We eat lunch, play for 10-15 minutes (during which I give her an update or two on how much time remains), and then head upstairs for toothbrushing, potty time, and stories before her "quiet time". I began calling it "quiet time" about three weeks ago after we went through three days' worth of screaming fits (despite routine) that ended in no nap. Now, my daughter knows that during "quiet time", she must stay in her bed for one hour (pediatrician suggested time frame) and either sleep or play quietly. To help her with this, I allow her to take a few books of her choosing to bed with her. Most days, she is asleep within a few minutes. On more defiant days, I just remind her that she doesn't have to sleep, and just saying that seems to calm her enough that she ends up sleeping anyway. I think that she really just didn't want to be "made" to sleep each day. And on the rare days when she doesn't nap or doesn't sleep well, we make a point of getting her to bed at least 30 minutes earlier than usual; sometimes she even asks to go as much as an hour before her scheduled time.
My one last piece of advice is to be careful with the car-ride method suggested by another mom IF your son is the type who cannot be moved from car seat to crib without waking. If I am not home in time for lunch with my daughter, and she falls asleep for even five minutes in the car on the way home, she will not go back to sleep for a full nap that day, ever. I know several toddlers who are like that, so I just wanted to share that.