HD Realtek mic-in (external mic) wont work. Windows 8

My computer is a Toshiba Satellite C55-B5302 and I have Windows 8. I only bought the laptop 5 weeks ago. I have not been able to get my computer to hear anything from my external device when I use the mic/headphone combo jack. I have an adapter plugged in that turns my 3 conductor 3.5mm end into a 4 conductor 3.5mm end. I have set everything up using HD Realtek and can see the icon for the mic-in on my list of enabled recording devices. However when I play media the sound bar doesnt move. Ive checked with my recording programs and they cant hear the mic-in either. I've checked and apparently all my drivers and software is up to date. I even re-downloaded the recording device drivers and nothing happened. Is there a way I can download a different driver for these devices. I have seen loads of other forums where people had the same issue with their HD Realtek but nobody was able to help them. Is there anything I can do aside from buying a 3.5mm to USB adapter that will make my computer hear the mic/in?

Thanks

Do you have the "Stereo Mix" set as the default Recording Device? If some other device, such as an internal mic is set as default no other device can be used in most systems. Setting the Default Recording Device as Stereo Mix then any recording device will be heard.