So try the usual tests.
1. Reset all the HDMI ports. Like this: Unplug all HDMI cables (just one end will do) and remove mains power to the set for a few minutes. Power on, and test.
2. Be sure other devices work on those HDMI ports.
After that, call Sony to see what they can suggest next.
Again, I have a clue why this happens, but no user serviceable parts and too often it's a Samsung TV.
About a week ago, my PS4 suddenly stopped showing any video/audio when I would turn it on. It's connected to an Insignia TV. The TV shows that something is connected, but displays 'no signal,' or sometimes a blank screen. I've tried different HDMI cables, the TV's other HDMI port, and another TV (which worked but using that TV permanently isn't an option.) Any help would be greatly appreciated