There’s always solution to every problem. It’s just how you find that solution in different methods.
As we know, blackberry devices always have many issues, this time i have issue with headset. I use curve 3g and headset was not working when i play music or video. I tried to manipulate the jack and it worked when i pull it slight. Then the problem reoccured, i tried the same way but it didn’t work. To make sure whether the headset is not broken, i plug the other 3.5mm jack(nokia 5800xm headset, sony erricson headset), it didn’t work either (usually it worked, so basically the problem is not in headset)
So i checked on the internet, many people experienced the similar problem. From there, i conclude that there are some ways to make it work again:
1. Pull the battery when the power is on and the headset is plugged in. Reinsert the battery. (It worked in my case)
2. Play video or music, then press answer button in headset
3. Just give it a go +_+
Hope this also work in your case. Good luck! 
