BIOS AND Vista Not Recognizing 2nd SATA Hard Drive

After Vista upgrade on Toshiba Qosmio G35-AVA600, one of my SATA drive stopped working. It is having two 80GB hard drive in the system. Both are configured on RAID. But after Vista installation one of them just disappeared. It is not shows in BIOS nor in Disk Management. The laptop is not so old, so there are less chances of hardware failure. I am manually trying to locate the second drive, but still failed to do that. The thing that shocked is the drive is not at all visible in bios also. It looks Vista upgarde is just a waste of time. How can I bring it back.

You said that the drives were configured on RAID. So there is a internal raid controller in your system which is not compatible with Vista. You have to either put your hard drive on independent mode so that they can be detected separately and you can use both of them. Or you have to find proper raid drivers to get the second drive back. Your job to restore your system will be much easier if you have any kind of recovery partition in your system.