Skype does not recognize the microphone
If
Skype doesnot recognize the microphone, then to resolve this problem, just check 3 points:
In the Control Panel
- Go to Control Panel, then Sounds and Audio Devices
- The Playback tab, check that nothing is on mute
- Click Advanced and verify digital speaker is not checked.
- In the Recording tab: check that microphone is checked
- Click Advanced and check that nothing is checked.
In Skype
- If the microphone is not recognized, go to Skype/Tools/Options/Audio Settings/Microphone
- Select microsoft default device.
- Uncheck the "let Skype manage my audio devices.
Update driver sound card
If the microphone is still not recognized, it is perhaps a problem with sound card. In this case:
- Check the brand and model of sound card.
- Download the latest driver.
- It may also be useful to go to the manufacturer's website (hp, packard bell etc) and try to download the audio drivers.
Thanks to Tabyria for this tip 
Audacity does not recognize microphone