i am having a problem with my creative speakers

i don't know what happen,but after installing gtalk ,i have done a few adjustment with my speaker settings and i am not hearing any sound from my speaker. actually my head phone was not working(headphone is not playng any music,but it is only give me some sort of buzz sounds).
So i thought i could restore my computer at earlier time,then i restored it ,then my problem was solved.but the headphone is still having the same problem.but i what to know the cause of speaker problem ,but i have no idea!!!@!