airport card not showing up

Hello I had this happen before but do not remember how to ping the card. it normal works then it acts like i don't have one when I go to network diagnose airport is not available. can someone tell me again how to do so
thanks

Check the antenna is not loose and it appears in System Preferences and Apple System Profiler "About this Mac" >More Info>Networking. Alas the cards do go to card heaven from time to time.

no it does not show up in system profiler last time it has done this same thing i had to do what is called a ping which i found on the web how to do just cant find it again it has something you do when you start the computer up and then it worked fine

Have a look at this from Apple Discussions:-

Apple - Support - Discussions - Airport Card Talks to Router, But Not ...