First, you need to check the physical connection. Make sure that the jack is connected to the right sound port.
Second, check the volume properties and make sure that the volume control is set to maximum, and make sure also that the "MUTE" box is unchecked. Try to adjust the volume of the speakers as well.
If same problem occur, might as well, try to use a know 2-channeled PC speakers, so that you can test if the sound card is working or not.
Answers & Comments
First, you need to check the physical connection. Make sure that the jack is connected to the right sound port.
Second, check the volume properties and make sure that the volume control is set to maximum, and make sure also that the "MUTE" box is unchecked. Try to adjust the volume of the speakers as well.
If same problem occur, might as well, try to use a know 2-channeled PC speakers, so that you can test if the sound card is working or not.
Thank you and good luck!