I do not understand why audacity does not record sounds from computer … it went fine until I had to format the pc … I tried them all but unsuccessful … audacity does not “hear” the audio computer … can anyone help me? Thank you 
If you want to record the sounds coming out of the soundcard there are [u]several methods[/u]. WASAPI loopback usually works best for Windows 8 or later.
Dear DVDdoug with WASAPI I solved the problem. Thank you very much !! 