Sounds like your Avionics is off. Because there is no Master Avionics Switch, you can't turn the Avionics on, unless you create a Keyboard Command for it (mine is CTRL+SHIFT+A). You can try pressing CTRL+E (default for engine start) as turning the Avionics ON is a part of the CTRL+E engine start procedure.

The way to avoid the Avionics being OFF, is to make sure that the Avionics is ON in the default flight. My default flight is the C-172, cold-n-dark but with the Avionics Master Switch ON.

Hope this helps.

Mark