The Dink Network

It's probably defaulting the recording device to stereo mix rather than your microphone, which is in fact the system audio. Open recording devices and see if your microphone is in there, if not make sure it's not disabled and invisible - Right click anywhere in the list of recording devices and make sure 'show disabled devices' and 'show disconnected devices' are both ticked, once they are ticked if you see your microphone come up in the list, right click on it and enable it.

If none of the above works than I'm out of ideas.

thanks for the idea, but this is the first thing that came to my mind when the problem occured