Insert disclaimer here. Even if you follow these instructions exactly, it may not work for you. In fact, it may make things worse. If you proceed, you do so at your own risk. I don’t have the time to try to make it work for you so you are on your own. YMMV.
We just got some Dell Optiplex 760 PCs. They came with XP Pro but I also wanted to install Ubuntu 9.04. After installing Ubuntu most things worked, with the notable exception of the PC’s internal speaker.
If I plugged in a headphone, I could hear sounds being correctly played. But nothing was coming out of the PC’s internal speaker.
Step 1. is to open the Gnome volume control by starting the Gnome “Run Application” dialogue box via Alt+F2 (that is, hold the Alt key while also pressing and holding the F2 function key).
Step 2. This should open the dialogue box (shown above) into which you type:
And then click the “Run” button on the dialouge box (see image below).
Step 3.If you see a slider marked “Beep” (if you don’t, skip down below) make sure there isn’t a red line through a circle below the slider or that the slider isn’t at the bottom most position. If you see the red line and circle, click on it and that should un-mute that device. You may still need to move the sliders if they are at or near the bottom (I used my mouse to move the sliders to the top most position). Done.
Step 4.If you don’t see a slider marked “Beep”, you need to click on the “Preference” button and then scroll through the devices until to see “Beep” and check mark that device.
Step 5. You should now see a new slider marked “Beep” and you can see if it is muted (slash through red circle) and or the sliders are at the lowest setting. If either or both is true, do as above and click on the circle to un-mute the device and move the sliders to the topmost position.
After un-muting and moving the sliders to maximum, it should look like this image below:
If the above does not get your internal speaker working, you could try the Ubuntu troubleshooting guide located here: