if you can play sounds and music , and if your windows playing sound when you start it then your sound card is ok , if not then go to the next steps.
1-go to device manager and take a look on the audio driver if it is showing a question mark then reinstall the audio driver and restart your pc .
2-make sure that the audio and video pci cards is seated in its slot well.
3-make sure the audio wire is not pluged into the cd writer ( only power supply jack is connected to your cd writer along with data cable )
4-make sure that the cd roms are defined correctly if you have more than one cd rom or writer ( one cd rom should be master and the other is slave ) the data cable end should be connected to the master cd rom , and the middle jack should be fixed to the slave cd rom.
5- try to change the power supply jack to the cd rom with other one from power supply .
also check if you have connected the power supply to correct ac , some times power supply can cause a lot of problems if its not producing a correct volatage to the drivers .
bye