Ok there are two ways you can do this. First is the easiest, just look at the top of your keyboard, and there should be 3 keys with pictures of speakers on them. The first one might be located on the F3 key, it is just a speaker. The next one might be on the F4 bottom, it has a speaker with one sound wave next to it. The third one might be on the F5 key, and that one is a speaker with three sound waves next to it. To turn you volume up push the one with 3 sound waves, to turn it down push the key with one sound wave. To mute your computer push the key with only a speaker on it.
Ok now if that doesnt work then you will have to go to your SYSTEM PREFERENCES. A window will open and under the category 'hardware' you will see an icon for volume , click on that. This will take you to a new window with all your volume controls. Make sure the mute box it unchecked.
Ok now if that doesnt work then you will have to go to your SYSTEM PREFERENCES. A window will open and under the category 'hardware' you will see an icon for volume , click on that. This will take you to a new window with all your volume controls. Make sure the mute box it unchecked.