The cable that you've mentioned (blue at both ends) is a VGA cable which can carry only video signals. This cable does not carry audio. In order to carry sound, you either need to connect another cable from your audio port on the computer (green socket) to your TV or else if your TV has HDMI Connectivity and your PC too has HDMI, then connect both using an HDMI Cable. HDMI Cable carries both video and audio. However, make sure that your graphics card on the PC has sound enabled on the HDMI Port via S/PDIF.