crapkiller

Hello, i have a micro phone that i think is broken. Here is the problem

When you talk into the microphone, it sends the sound into the speakers (Like an intercom or something). That part works, but things such as sound recorder, dont recognize the sound from the microphone. I have tried sound recorder, camtasia studio 5 recorder, and steam sound recorder. Non of them work and they all have the same problem. It was working just yesterday and all of the sudden it stops working. I tried restarting the computer, making sure it wasnt muted or off. I raised its volume, i screamed into it. Nothing seems to work. But what confuses me is that it can send the sound into the speakers but not the computer. I am not a technically inclined person but could this mean there is something wrong with my computer? A sound card or something? If i remember correctly this has happened before and it just fixed it self and that was the end of it. But i want to know if i should just get a new microphone or would that be a waste of money because its the computer that is broken?

EDIT: I tested with another computer and it worked fine. Yet it still wont work with this computer. Could this mean that this computer is broken? (Please tell me no? Id rather have to replace a 20 dollar microphone than a several hundred dollar computer!)

EDIT: The first time this happened was on a different computer!

Thanks!