Siri not working on my MacBook Air, and can a software update fix it?

Siri not working on macbook air 

Siri can't hear me, but all microphone settings are checked in. Also Siri doesn't speak. It just doesn't work. It's been like this for a while and i'm sure it did work before. I've read somewhere that a software update could cause this and there is nothing that I can do to fix this. Is that true?

[Re-Titled by Moderator]

Original Title: siri MacBook Air