Lost audio output

I’ve lost audio output in general.

I can hear error bongs from Shotcut but I’ve lost audio from my clips. I can see the audio meter dancing around nicely but can’t hear anything.

I’ve exported a clip and can hear the audio when played in a different player.

Any ideas?

Please provide basic details like OS and versions.
Check your volume level on the shotcut player controls. There is a volume button there, which can also be switched to mute.