There are number of reasons your computer may no longer give sound. For a step-by-step tutorial to help you identify and fix common sound problems.
Check the Volume Control Settings
1.Click the Start button , and then click All Programs->Accessories->Entertainment, then Volume control. Alternatively, just click speaker icon in your task bar.
2.Check the volume and mute settings.
3.Then check the sound. If it is not working follow the below instructions.
Delete the Sound Drivers and Reinstall
1.Your sound drivers may have been corrupted or may be missing. For windows XP, follow these steps.
2.Click the Start button, Go to Control Panel and then click System. Click the Hardware tab, and then click the Device Manager, then “Sound Video and Game Controllers.”
3.Click your sound device named in the Device Manager, and then right click select the uninstall option. Remove all the listed sound devices except Audio Codec and Legacy Audio Drivers.
4.Restart your computer. Reinstall the deleted Audio drivers if you are using in your system recovery CDs.
Some mobile PCs have an external volume control on the outside of the case. If you’re using a mobile PC, check the external volume control.
Make sure your headphones are not plugged into the line out (headphone) jack of your sound card or computer. When you plug in headphones, most computers automatically cut the sound to the speakers.