If you're not hearing sound but are seeing video on your Samsung LED television set, something is configured or hooked up incorrectly. There is no other explanation for the lack of sound across all video sources. To correct this problem, you have to go through all of the devices connected to your LED TV and make sure they are hooked up properly.
Check the volume level on both your Samsung LED TV and any attached home theatre receiver. If you've connected your TV to a home theatre, the volume is now controlled by the receiver and not by your TV. If the volume is turned all the way up on the TV but is muted on the receiver, you're not going to hear any audio from any of your connected devices.
Verify that any devices connected via HDMI use a single cable for both audio and video. HDMI is capable of transmitting audio and video over one cable, but that doesn't mean your connected device is. Certain devices use HDMI for video and a separate audio cable for audio. Make sure your device uses HDMI for both types of signals by checking the user manual that came with the device.
Check your cable connections to all connected devices. Your audio cable will need to be connected firmly to both devices to successfully transmit a signal. The fact that you're seeing an image but hearing no audio suggests that a problem is present with your audio cable. Make sure the cable is firmly connected and, if necessary, replace the cable with a new one and try to use your Samsung LED TV again.