Lost my volume output control. Headphones work, but not the computer.
After using my headphones to listen to music on my IMac with OS10.10.3 system, I've lost my volume output control. The volume icon on the top of the screen is greyed out. When I open System Preferences Sound, i get a message that this device has no output control. Anyone know how to retrieve that item? Mean while the headphones still work, just no volume when headphones are not plugged in.....Thoughts?
MacBook Pro, OS X Mavericks (10.9.5)