Shark 75160HS 2.1 Multi media speaker system

Question

I have connected the speakes and subwoofer to the computer and although there is clearly power going through, I have no sound coming through the speakers. I had this problem with previous speakers and thought that the fault was with them but these are brand new!!!I have checked the volume settings onthe computer and everything seems to be in order but still no joy!Can you help?Thanks P