Since the failure of one drive brought down your system, I'm assuming you're running RAID 0. RAID 0 stripes data across all drives in the array. Because of this, if you lose one drive, you lose all your data.
Try googling for some free raid repair software.
If you want true redundancy, I suggest that in the future you use RAID 1 or RAID 5, anything but RAID 0. Also, regardless of which RAId you run, always make backups.