so my laptop doesn't have sound. like something happened to linux and it doesn't have sound. my dad installed ubuntu 9.04 and i looked at the sound; it has a sound card again and the icon is working again but the sound is not coming out of the speakers, the head phone slot isn't working either. why is it still not working? i checked if it was on mute and it wasn't. how can i fix this?

oh and how can i put linux on safe mode? like my dad put linux on this weird mode where everything was on defualt and my wireless was working when it wasn't and my sound was working again... does anyone know how to get to that default mode?