no sound coming from speakers ?

If you hear no sound coming from your speakers, there could be several reasons:
1) Check to see if the speakers are powered on.
2) Check to see if the cable is plugged into the speakers and the green jack in the back of the computer.
3) Check to see if the speakers are muted in Windows. Do this by clicking on the speaker icon in the system tray. It has a place to check to mute the speakers.
4) Check to see if the sound devices and drivers are loaded. To do this go to the control panel and click on "sound." Then click on the sound tab. Choose one of the Windows events that has a sound associated with it and preview the sound by clicking on the arrow to the right of the listing. If the arrow is dark and when you click on it the sound seems to be playing, then the drivers and sound card should be functional. If the arrow is grayed out, then your sound drivers are not installed. In either case, try reinstalling the sound drivers.
5) If you've tried all this to no avail, try with another set of speakers.
6) One thing that may work is to do a system restore back to the time the speakers were working.
7) If nothing works, I would suspect that you have a bad sound card. Unfortunately, these days sound is integrated into the motherboard, but you could install an add-on sound card.