Sound card and driver

May be the drivers are not installed if so install the drivers which will be available in the manufacture cd given to you at the time of purchase ...
you can check the audio driver is installed or not from the following :
control panel >(classic view) sound & audio devices ....
if you have installed the audio driver it will display in this other wise it will display that no audio driver installed ....
if you already installed but also if it is displaying like that means there must some conflict in the drivers you can check that from the following :
control panel> (classic view)system>hardware>device manager
in this check the multimedia audio codecs are installed or not ...
check is there any conflict by going to the properties by clicking on the audio codecs ....
if so reinstall the driver by uninstalling it .......

or there may be some problem in the speakers pin which you insert it to the audio port or you might have connected to the wrong port( you must connect it to the green port) or the audio device might have got disabled in the bios settings just go to bios (by pressing F2 at the time of booting)
& check it if the audio device is disabled or enabled ....
if it is disabled then just make it enable .....

these are all the possibilities just have a check with these basically .....

if these are seem to be correct then there is only one last chance the capacitor near by the audio port is burnt out so just open the motherboard & check it is there any burnt mark or smell ...(something there will be no burnt mark )
after this just have a check that the audio device pins are connected to the motherboard header or not there will some small 10 or 9 different pins which must be correctly connected to the header .if they are not connected then also the audio doesnt work ......

if the capacitor is gone then you must get it replaced by the motherboard technician ....

just by having the check with these your problem will be solved

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