Please try the following:
1. Check to see if the built-in speakers are being turned off.
2. The speaker volume might be turned to the minimum level.
3. If the computer is powered by batteries only, check that the battery packs are inserted properly and that they are fully charged.
4. If you are using an application that has its own volume control function, check that the volume has been turned up and not muted.
5. Check and ensure all volume controls in Windows® 98 are not muted.
Click Start->Programs->Accessories->Entertainement->Volume Control.
6. If any external speakers are connected to the computer, check that the speakers are properly connected and the volume is turned up. If the speakers have a mute button, make sure it is not being muted. If the speakers are powered by batteries, check that the batteries are inserted properly.
7. If you have connected headphones or an audio cable to the Headphones connector of the computer, please disconnect the cable and see if there is any sound.
8. Please ensure that the sound port in the Device Manager has no conflicts or errors.
Click Start and then click Settings. Double-click System and click Device Manager tab. Check and see if there is any X or ! marks stated in the Sound, video & game controllers section.
To listen to an Audio CD's on the 505 series computers, you will need to plug the headphone on the CD-Rom drive.
If none of the above solves the problem, please send the set in for checking.