Maybe the port in which the HDMI cable is plugged in doesn't work properly, due to a physical damage of some kind. Try plugging in the HDMI cable in another port on the TV.
Note: If that didn't work, check out the other solutions.
Maybe the HDMI port(s) on the sender (e.g. a computer) and/or the receiver (TV) is (are) dirty and as a result of this, there is no picture and/or sound to the TV.
Try cleaning the HDMI ports using a small toothpick to remove dust lumps, if any, and then pour some rubbing (isopropyl) alcohol on a small piece of cotton and clean the ports until you remove all the dust.
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