Since it's obviously the microphone which is the problem, are you sure that it's actually plugged into the correct socket? It's quite a common fault for people to plug it into the 'line in' socket, rather than the 'microphone' one.
Also use the "test hardware" setup in Control Panel/Sounds & Audio Devices/Voice tab.
Also open sound mixer and Properties .. select "recording" and check mic is selected and turned up.
. . . and I hope that you're feeling good (if somewhat frustrated) as well ;-)
You've stated that the inputs aren't muted but where are the sliders? Right-click on the loudspeaker symbol (at the bottom right of your screen) and select 'Open volume controls' (or something similar - what you see on your screen might not match exactly what I've got on my mine). If there's a slider specifically for the microphone input then (obviously) that's the one you want to maximise. If not, push the 'line in' slider to the top. (It might also be worth trying the 'Wav' slider at the maximum setting).