Check the Recording sound panel.  It may be disabled there.  Actually, "Stereo Mix" if available should be set as Default Recording Device.  If not available, set the mic as default. 

Have you tried both the front and rear mic connections?

both headsets are usb and I have tryed front and back ports, this issue just started last 3 or 4 weeks It may have been windows update. There are other posts online about the update issue with realtek sound systems but I have used the fixes with no luck.

thanks for reply

wecelliott49,

What BIOS version are you running? I just upgraded to the latest (v1.3.6) per the Dell notes the enhancements are increased system reliability. Since you tried uninstalling and reinstalling the RealTek driver with no luck and tried the various fixes (Windows update may have caused issue with sound) you may want to try the latest BIOS update (if you haven't already) to see if this may remedy your issue. 

USB sound devices do not use the PC's sound card, thus its not a Realtek problem.

Try a "reset" of the USB devices.  Plug one in then go to the Device Manager, Sound Section (if listed or USB if not listed) and uninstall the device in the Device Manager.  Disconnect the USB device then restart Windows.  After Windows starts, plug it in and see if it works.

I am running 1.3.6 bios, I am leaning to the windows update issue, I will try reseting usb.

thanks again for help