I'm posting a solution I've found as other people may have the same problem.
My grandsons HP laptop has no Line In socket, only a microphone socket.The drivers for the built in Conexant sound card don't support a stereo mix function, only a microphone, therefore programs to record music off the net used the microphone channel and the qualiity was poor.
I've found a program called
FREECORDER which is excellent(and free).
It is in the form of a toolbar which can be hidden when not in use and uses it's own drivers to record straight from the sound card in WAV or MP3 format.
This has solved the problem of No Stereo Mix.