For fear of sounding blunt, you've got a two choices. you either leave your NSR off the road with a broken sprocket, or you pay for a replacement. I'm sure that if you put a wanted add up in Andy's classified section then someone will come along to help. But seeing as you're in the philippines then the shipping's gonna hurt what ever way you look at it.

Or you could weld the teeth back on seen that done here in Thailand before.

However, if your sprocket is that badly damaged then your chain is probably well past it's best too, and they aren't cheap. Not for a good brand.

Bite the bullet, pay the money and love your NSR.