I cannot hear any sounds on the computer
If you cannot hear any sounds on your computer, for example when you try to play music, go through the following troubleshooting tips.
Make sure that the sound is not muted
Open the system menu and make sure that the sound is not muted or turned down.
Some laptops have mute switches or keys on their keyboards — try pressing that key to see if it unmutes the sound.
You should also check that you have not muted the application that you are using to play sound (for example, your music player or movie player). The application may have a mute or volume button in its main window, so check that.
Also, you can check the Applications tab in the Sound GUI:
Check that the speakers are turned on and connected properly
If your computer has external speakers, make sure that they are turned on and that the volume is turned up. Make sure that the speaker cable is securely plugged into the “output” audio socket on your computer. This socket is usually light green in color.
Some sound cards can switch between the socket they use for output (to the speakers) and the socket for input (from a microphone, for instance). The output socket may be different when running Linux, Windows or Mac OS. Try connecting the speaker cable to a different audio socket on your computer.
A final thing to check is that the audio cable is securely plugged into the back of the speakers. Some speakers have more than one input, too.
Check that the correct sound device is selected
Some computers have multiple “sound devices” installed. Some of these are capable of outputting sound and some are not, so you should check that you have the correct sound device selected. This might involve some trial-and-error to choose the right one.
Open the Activities overview and start typing Sound.
Click on Sound to open the panel.
Under Output, change the Profile settings for the selected device and play a sound to see if it works. You might need to go through the list and try each profile.
If that does not work, you might want to try doing the same for any other devices that are listed.
Check that the sound card was detected properly
Your sound card may not have been detected properly probably because the drivers for the card are not installed. You may need to install the drivers for the card manually. How you do this depends on the type of the card.
Run the lspci command in the Terminal to find out what sound card you have:
Go to the Activities overview and open a Terminal.
Run lspci as ; either type sudo lspci and type your password, or type su, enter the root (administrative) password, then type lspci.
Check if an audio controller or audio device is listed: in such case you should see the make and model number of the sound card. Also, lspci -v shows a list with more detailed information.
You may be able to find and install drivers for your card. It is best to ask on support forums (or otherwise) for your Linux distribution for instructions.
If you cannot get drivers for your sound card, you might prefer to buy a new sound card. You can get sound cards that can be installed inside the computer and external USB sound cards.