Microphone not registering or working in ...

My microphone is not working on skype.
On the echo123 test I am getting one of 3 error messages each time I try this.
1) Your microphone is too low and other party will not be able to hear me. That is true. I was talking to other party when the sound just got lower and lower until they could not hear me. At that time, echo123 could still hear me, but the sound was low. But the other party couldnot hear me. Now the echo123 also cannot hear me, and it is now telling me either one of the following
2) Your microphone is on mute - please unmute. But my microphone is not on mute. I have checked everywhere I can think of in my entire system and the thing is not muted anywhere.
3) Your microphone is not connected. But it is connected.
I know the microphone itself is working fine because if I go to accessories>entertainment>sound devices I can record no problems, so it is not the microphone.
I have uninstalled and reinstalled skype. This did not fix the problem.
I have uninstalled and then installed the latest version of skype. That did not fix the problem either.
I have installed the latest versions of realtek. That did not fix it either.
I have stopped skype from monitoring and autoadjusting the sound. That didn't work either.
I have also tried cleaning the jack plugs - just in case they were dusty or something. No change.
I have changed headphones - just in case that was the problem - but it wasn't.
I don't know if this has something to do with anything, but the problems started soon after I purchased some skype $ to call an overseas number on skype.
Does anyone have any ideas as to what I can do to get my skype working.
Allison Walker