Your son is obviously going through a hard time. I can relate because I was estranged from my own father for ten years. I dropped out of school, ran away from home, and generally did whatever I could to make a giant mess of my life. Unfortunately, the problems your son is having will not be corrected overnight. Fortunately, your presence in his life can have a healing effect on him.
My suggestion would be to let his mother handle this issue with your son at this time. You showing up after ten years and trying to assert your authority over him is not going to have the intended effect - and will probably have the opposite. I think he will resent it if you go that route.
In my opinion, I think you should focus on re-building your relationship with your son and earning his trust and respect. Only then can you have any impact on his behavior. This will take time a commitment on your part, and expect that he will push you away at first. But, if you show him that you're going to be there, that you love him and care about him, and that you regret the years that you lost with him, I think he will come around.
Good luck, and congratulations on the opportunity to reconnect with your son.