I have had this issue since installing ubuntu 12.10 last week. I have read every article I could on this and nothing seems to work. I have installed pulseaudio volume control and tried every configuration in there, unlocking the channels and running a recording program to select a device in the panel.. I have tried every option in alsamixer from terminal. I have used gstreamer to try every different configuration in there. I have reinstalled 12.10 and even that didn't help. Any assistance would be appreciated. Computer is a compaq cq50-100CA. Processor is AMD Athlon Dual-Core QL-60 × 2 and using a proprietary graphics driver NVidia GeForce 8200M G/integrated/SSE2/3DNOW! and have Gnome 3.6.2 installed. Thanks in advance!
Try to install Pulseaudio Volume Control (pavucontrol) and check if your input port and profile selections for your sound card are correct. Such settings appears to be missing in the regular Sound Settings in Ubuntu.
General troubleshooting from here: