HDMI Ports Suddenly Not Working

Verizon Fios Cable box signal still works fine on TV. The trouble is with the HDMI ports. We have an Apple TV, Sony BluRay, and LG DVD/surround sound unit each plugged in to the HDMI ports. None of them work, except for the Apple TV, but that signal shows with "snow" running over it. For the others, a "no signal" message appears on the screen when you select their input. I should note that each of these devices has been plugged into these ports for two-four years without trouble.