No sound is coming from computer

Check to see how your output is configured. Go to System Preferences > Sound > Output, first check to make sure Mute isn't checked toward the bottom right. Or adjust the volume slider to where you want it. The other thing is in the list box above, look to see what is selected as your output source. There may be other devices still listed that you don't have or aren't working. It should have selected at the very top Internal Speakers, or possibly Headphones (if you have something plugged into the headphone jack.