There is no sound on my insignia flat screen what do I do

Try hooking up the powered PC speakers to the AUDIO Line out RCA jacks to see if you get the sound there, if you do, then the problem can be in the power amp section (make sure to check the on screen sound setup menu that the speakers are not set to OFF), if no sound at the RCA jacks either, then the problem can be in the sound processor circuit in the main board.