Accessing the bios

[Christian]

Hi all,
I just have a question. My external sound card has stopped working so I need to enable the integrated Realtek soundcard but that's disabled in the bios.
Does anyone know if I can press the first letter in the bios for r to restore default options? Or is there some utility that allows me to change bios settings under LInux?
Its Ami bios.
Many thanks,
Christian