Music was not 'discovered' in the true sense of the word. It has evolved, from the earliest days of man, to express emotions, and has developed in sophistication and depth, as our species ahs become more complex and expressive. As long as man has been able to make sounds, there has been 'music' in its truest form, but you could never say that someone 'discovered' it. Similarly, people say that 'popular' music was created the day that Elvis recorded that session in Sun Studios, but he didn't work in isolation - thousands of other musicians were working, and influencing the sounds Elvis made. That's what makes music so amazing - it has no beginning, and indeed, no end.