microphone input slider is turned down and won't turn up

I have a Windows 7 computer and I installed the Audacity exec file. The microphone input slider is turned down and won’t turn up. When I try to slide it to the right to maximize the input, it automatically slides back to the left. The recored sound is too low to hear and the waveform display barely rises above a flat line. The microphone is plugged in correctly and there is no inline volume control on the microphone itself. The microphone recording control on the computer is turned all the way up. Does anyone know what is wrong?

Audacity disables the input slider if it cannot directly control the system slider for that input, so that they would operate in tandem.

Use the mic’s slider on the “Recording” tab of “Sound” in Windows instead. Check out these links:

http://wiki.audacityteam.org/wiki/Mixer_Toolbar_Issues#vistacp .