Sum up,in Chinese :
1.拉 is used to stringed instrument which has to be played with a bow on bowstring.
ex.拉小提琴,拉二胡,拉大提琴,拉板胡....
2.弹 is used to musical instrument which has keyboard or strings and which is played by plucking with fingers .
ex.弹钢琴,弹电子琴,弹吉他,弹竖琴,弹琵琶,弹古筝.....and so on
3.手风琴:As an especial instrument,both 弹and 拉 can be used.
Because it has a keyboard and the action includes pleating and pulling bellows when it is played .