Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I'm sorry to hear about the problem lasting so long.
What do the TVs in the house show, when they are turned On?
If they all get the same signal, the same TV service (when it is working), then you need to go to the 'box' that feeds TV service/signal to all of them. Check the status of its lights, note down which lights are doing what (according to the labels next to each light, and whether they are On, colored and/or flashing.)
Then unplug the TV 'box' from the power.
Leave it that way for at least 20 minutes, to cool of and reset.
Then plug it in to power again. Wait 2 minutes, note the lights status on the TV 'box', then go to the TVs, turn them On, and see whether any or all of them now work.
Let me know more about the setup you have, the TV service you have, and what happens and what you observe, and if there is still a problem I will use that data to help you further as needed.