How do I get my mic to work?

I just bought a new mic and it wont work. I have already checked and made sure its was not muted. In the device manager I went under show hidden devices and it shows a (!) in front of Logitech Mic (Communicate STX) and USB Audio Device. When I try to update driver on the Logitech Mic it says "There was a problem installing this hardware: The drivers for this device are not installed (Code 28)," and when I try to update driver for USB Audio Device it says that its missing a neccessary enrty and may be because the INF was written for windows 95 or later. How do I fix this and get my mic working?