iTunes refuses to play video or audio ... the bars which show something is playing do NOT move but the II shows as playing.

2 Day old MacBook Pro. 16G with 512G running 10.13.3. All of a sudden the speakers do NOT show in System preferences and the volume controls do not work. When I go to play songs or video on iTunes, nothing works or moves. The screen goes black on video play but the play bar doesn't move. When I go to YouTube or play anything in QuickTime, I actually get the video to play ... but of course, NO sounds ... even when I put a jack into the audio out port. Color me ... AT A LOSS!