No sounds are coming from my speakers or headphones
firstly you check,sound driver is available in your system or not,as per your comment i think sound driver is missing in your system.
follw the given instruction and check sound driver is available on not.
1- right clieck of "My Computer" icon
2- Chose the Manage option.
3- Go to the Device Manager option
4-Check Audio,video driver (if yeloow indication are showing in audio,video option)
Thats means sound driver are missing or need to be upgrade.
(Go to control pannel and open "Sound and Audio Devices" properties if all the options under it is disable thats means audio driver is missing)
When you parchase the system you carry a motherboard CD,put in that cd into cd drive and install the appropriate drivers,if you have no Cd in that condition you download the drivers from net,