check that the sound card drivers are installed properly
go to control panel > sound and audio devices
go to microphone/recording tab, make sure that your sound card/microphone is selected for recording device
open up Volume Control > go to options>properties, switch to recording option, hit ok and check that microphone is all the way up
make sure that your laptop/software(skype) doesn't have a microphone mute button/function
if none of those seem to help, let us know