New HP 6730 Celeron – No Sound?

My Mother just bought this Hewlett Packard 6730 Celeron Processor, Win98se, and has no sound when a card is with music, etc. Her Callwave internet answering machine is working properly, and she gets the start up giggles coming through fine on the external speakers. Could a sound card be missing or something? Is it a setting that is off? I need some input before I tell her what to do. She is 65 yrs. old, bless her heart!