Apple TV 3 rd gen not responding

Have you tried restarting or resetting your ATV?

Here's a link describing how to do both:

Reset Apple TV - Apple Support (CA)

If neither of those help you can contact Apple for further assistance:

Apple TV - Official Apple Support

If it is a 3rd gen you can try unplugging the Apple TV, wait 10 secs, and reconnect to see if it powers on appropriately. Otherwise, there isn't a lot more to do. Be aware that it is obsolete (also 13 years old so issues are more common)and most providers of the server based channels have dropped support so it is limited in what it can do.

However, if you have the Apple TV 4K (3rd gen) then Apple can assist if the force reboot doesn't work.

Identify your Apple TV model - Apple Support (CA)