No sound through HDMI cord when connected to Tv

My Samsung tv is no longer playing sound from my computer with the HDMI cord. I have checked my Sound Settings and HDMI cord is selected as the output volume source. If I try selecting the Samsumg tv as the output source it tells me "this device has no sound output" which makes no sense because it was working the night before. I have also changed the HDMI cords neither of them are working. I am getting pretty frustrated and am upset its no longer working. I am also worried that there is something wrong with my computer which is the LAST thing I want to hear. PLEASE help me! I love watching movies through my computer to the tv. Thanks!