Have same tv HP 42 plasma, red light is on but no image or sound. all I can hear is a click sound when I first plugged it and another one followed few seconds after. what could be the problem?

If the red light is on that means the power is not. Ensure you have pressed the power button on the TV. Also make sure you have a good source plugged in. In response to the above response, it may be a capacitor, but it's unlikely and you would be able to press the power button and see the light flash and then stay solid usually. You can also try the remote to power on the TV, just make sure the batteries are I properly.

Many LED TVs and other electronics have bad capacitors on their power supply boards. You can visually inspect them by opening the TV and looking for capacitors with bulging tops. If tou see any, replace them all in the power board section. Check to see if your TV is still under warranty first though.