microphone issues

well i recently bought a headphone mic set made by labtec. At first i had no problems with it after a couple of weeks of none use i decided to use them again whle playing an online game however they didnt work.
So i tested them in the control panel tester and the mic and ehadset worked fine. I then tryed sound recorder which also worked fine.
So i decided to try teamspeak again and msn but neither of them work i can hear the people im talkin to; but my sound isnt being recognised and they cant hear me.
If this makes any sense to anyone could someone please help. thanks

athlon 2500
512mb corsair xms 3200
radeon 9800np
80 gig hd