MacBook Sound Not Working

I recently plugged in speakers into my MacBook. After Unplugging Them My Built In Audio Did Not Work. Whenever I Press The Volume Up Button The Speaker Is Blacked Out And I Get A Little Restricted Circle With A Line Through It. When I Go Into System Preferences 'Built In' Does Not Show Up. But When I Turn On My Computer The Chime Does Play So My Speakers Are Functioning But It Does Not Work After I Log In.