I created a new project using the demonstration template.
When I went to record I got a popup asking me to calibrate. I
accidentally said no and checked the 'do not ask again' box. Now I
can't manually calibrate sound or manually change the input device.
What is worse, when I open up a previous project for which there is
recorded sound I can't play the sound! What gives? Any
Reinstalling shouldn't have been necessary. If you click Edit
> Preferences... > Global node you will see all sorts of
click boxes. This is where you may re-enable options that have been
turned off. I'm guessing that before reinstalling, you would have
seen that the check mark was removed for the option labeled "Check
audio input levels".