Yes she can use on board sound.
The bois will have to be changed.
If you don’t know much about bois it is better to look at motherboard manual.
You have to disable soundcard and enable AC97 onboard sound (remember to plug the speakers into the onboard sound jack)
Recommend removing and uninstalling drivers of dead card (if it is dead) it may be that the drivers are corrupt and the card is fine. You could try uninstalling and reinstalling drivers.
However leaving it in place and disabling it should not cause any problems.
Need more info in your O/S , soundcard and motherboard.