Forcing anyone to do something (teen included) usually makes people more entrenched in their desire *not* to comply. Usually, praise works better i.e. praising what he does well, dialogue, curiosity and respect work better as well (i.e. why does he not want to study)

It is a difficult question as many things need to be explored (that you can ask yourself): was he always reluctant in studying? was this a recent change? did something happen in his life and/or in his environment? what is his relationship like with you / his family? is he struggling with other issues? is he in therapy? Etc. There is no easy or quick-fix solution without addressing the wider picture surrounding this particular behaviour.