Half way through doing editing I lost audio.

So today I was half way through (or at least over half way) doing some edits to a new song and somehow I lost any audio signal.

I"m running through the steinberg USB box. That’s what’s set up in my device panel.

I’m able to hear itunes, youtube and stuff through my headphones (which is plugged into the steinberg box).

I tried to drag into the window a random MP3 but still no sound.

Can I get any help with what’s wrong ?