My remote will not turn tv on or off nor will it

I had the same problem with my LG 42PC3. With e few remotes around all programmed to control the TV all of a sudden stopped working. It was highly unlikely that all 3 of the remotes were defective or with bad batteries since the other components like stereo and Sat box would work with the same remotes. I assumed the problem lied with the receiver on the TV. It turned out to be the TV but not the receiver itself. Let me explain, there is a "REMOTE IN" plug behind the TV to connect an external wired remote (why, I have no idea). I was explained that when you plug in an external wired remote, it deactives the IR sensor. But the problem was that I didn't have an external remote plugged in there. What happens is that some corrosion builds up in the connector behind the TV which causes the circuit to close and deactives the IR receiver, all that is required is to unplug the TV from power source, squirt some WD-40 (only a little) into the connector hole behind the TV and use any 3.5mm plug like a headphone jack and plug-unplug a dozen times to loosen any build-up in the plug which I did and now the TV receives the signals from the IR remote. Cool, how simple is that. I hope this helps anyone out there with the same problem.

First check the remote. You can do this if you have a web cam. Open up the web cam. In the dark point the remote control into the webcam, and you should be able to see pulsating lights coming from your remote. Thats because webcam can "see" infrared" which is invisible to our eyes. If you don't see that IR light using webcam, the remote is bad. Try doing the same test on another remote to confirm. If you confirmed that the remote is indeed good, It is unlikely that the IR sensor(not an rf sensor) is bad. Out of my years of experience this never happened. You can also test the IR reciever in a TV, but it is hard to exlpain how to determine which pin is which. It has three pins. One is for power, and usually around 5VDC. The other is the ground(or negative for that matter). The last pin is where you connect a LED(light emmtting diode) in forward direction. If you point any remote to it and press any button the LED would pulsate indicating the IR is working. So it has three pins. To determine which is negative. Look at the circuit board where it was. Get a meter, set it to continuity, probe one end to a chassis ground, such as the metal box of the tuner, and find out which pin has continuity to it. Whichever one it is will be the negative. To find the voltage supply, find which pin is connected to the positive side of a medium size capacitor used for filtering. Maybe around 100uf rated at 16V. The last one would have the smallest trace since this is use to send pulsating signal to the processor inside the TV.