I read in your post that 2 out of your 3 disks are fine. So it's only data from that one disk that might be missing. Surely you have a backup of data that you would like to keep?
If not everything is on a backup (that can happen), then boot from a Linux disk and see what of those missing files you can move to an external disk from there.
When my computer started up today it said that one my hard drives (WDC WD6400AAKS-7) wasn't working properly. My RAID volume says that its status is normal and my other hard drive seems to be working properly.The one not working properly has "Error Occured (0)" under its status. My computer is unable to boot up and keeps going back to the screen with the RAID Volume and Physical Disks, and will shut down shortly after. I have a lot of data that I would like to keep and any help would be appreciated..