my audio volume in keyboard is disabled any help?

[stuart2102]

my audio volume in keyboard is disabled any help? how am i going to enable this again on my imac lion X OS its not working anymore my audio sound level of volume through my keyboard F12, what happen?

 

[emjaymert]

Did you inadvertently mute yourself? (f10) to check..hit f10 and see if your sound returns.If you are indeed muted this will unmute you.

 

[stuart2102]

Did you inadvertently mute yourself? (f10) to check..hit f10 and see if your sound returns.If you are indeed muted this will unmute you.

nope actually it happens in my snow leopard OS but what i always do is put headphone on audio jack then after that it will enable and everything will back in action but when i tried that trick in my lion X OS it didn't work