Raid hdd issues?

I went over to a friends house to work on their computer for them and ended up replacing their video card. As I was working on it I was messing around with their intel raid storage and noticed that it was not working anymore and it said the driver was not installed. I went into bios and checked and somehow the bios was now on ide instead of raid. How the heck it got changed no one knows because they have no idea how to get into the bios.
I have never had to do this before but what am I going to do to get the raid back on for them. Do I unhook one hdd and then go into bios and turn on raid and start the computer with one hdd and then tell it to rebuild? Would someone be willing to give me step by step instructions on how to do this if you know because I have never had to do this before. Thanks.