My HDMI port no longer works

Sounds like everything works. Your remote has an input menu. Have you cycled it around to the right component? i.e. HDMI1 or HDMI2, or DVD, even PC?
If not, try that.

I assume you have tried both hdmi cables from box to tv. If both works good.Cconnect to amp. Connect cable box also on other hdmi inputs like bd, dvd, etc to make sure the spesific port is not faulty. If still no picture try to lower hdmi video display on cable box. You amp may not be able to display the higher resolution.

Are you certain the cable box is OK? could be the HDMI output from cable box. Try a known good source, such as a DVD player using the HDMI inputs, if that works the cable box is the problem. If still nothing at HDMI input on the TV, then the MAIN PCB is the problem.

with hdmi plugged in take power cable out of apple tv ,put power plug back in then look to see if you have a signal....

As long as you have an HDMI port on each hardware, just insert the HDMI cable into the ports and it should work fine.
Hope this helps

I have the same problem.  It only occurs with my HD DVR (HDMI cable), not my blue ray (HDMI cable), or my xbox and wii (component video).  Video and audio cutout is random and drives the family nuts.  I am desperate for a solution.

HDMI ports 5 and 6 on the back of tv no longer are working. (We had a series of thunder storms so don't know if that is how they got damaged or if it was something else) but moved HDMI input cable to HDMI port 4 on tv and everything is working again. Service call placed for warranty service on tv to repair bad ports.

try 2 things, first use the rgb cables or video (yellow) cable and plug it into the tv using one of the imports..(vid 1,2,3 etc...) and see if that works. then check to see if you get a picture by not using the cable box, by pass it and connect it connect it in the uhv channel. also make sure you have it on the right input of the tv (meaning scroll through the input button on your remote to find the picture...i've done this a million times). still no picture try your dvd player input and if you have a vhs input see if that works. if it is the hdmi input...to be honest it's expensive and a pain to replace...

i know this sounds stupid, but have you "toggled" or "played" with the HDMI cables? are they the same manufacturer? HDMI channel connections are very fickle. If just one connection is not exactly correct, they go to a limp, no go status. Since they run at such a minimal voltage, i can't see them "blowing" the outputs on the devices.however....if your cable has a serial type output for video only, I would connect the hdmi convertor to it and see if it works.

The HDMI interface may have suffered a malfunction, this offten happens due to stray voltages on the ground plane. If you do not have electronics experience I would suggest taking the set to the shop and having it repaired