Last evening I was using my MacBook Pro to listen to music through an external speaker system, which I have done for a long time. Today at work I want to listen to music through the speakers in my computer but the sound control is greyed out unless I put my earphones into the sound out control. I cannot see in Systems Preferences a way to change it back. I actually did not do anything yesterday that I haven't done many times before. I just plugged in the wire from the computer to the speaker system and unplugged it this morning when I packed up the computer for work..

I have noticed that the in System Preferences, there is no longer an "internal speakers" selection..


thanks for your help in advance,