Q: sound problems 2008 mac air

Hello, davidfromloudon.  

Thank you for visiting Apple Support Communities.  

I would need a little more information regarding your system specifications and clarification on what you mean by sound card not recognized to provide a better answer.  However, here is a troubleshooting article that may help with this issue.  

Troubleshooting issues with no audio from built-in speakers on Macs

-Jason H.