Question

my friend is very shy and doesnot take in any sports and extracalicult acticities what must be the reason for this and how I encoirate him

Answer 1

Your friend must be shy of what the people will think about him and the other classmates will think ....especially girls....and this could only be fixed if he think that no one is watching him

Answer 2

find a sport or extracurricular activity that your friend is most  interested in and give him company to participate in events.
i know with personal experience that once he is appreciated for doing something he will gain interest and want to do more.
as for what is the reason behind this well.. he must not have interest in any activity and dosent believe he is capable of doing something creative and worth wile .