RAID5 array on a newer Intel controller, using 4 SSDs. One drive offline + another flagged error = array down.
1. Intel's answer: you're screwed
2. Community answer: flag all RAID members as non-RAID; recreate array with exact same type and stripe size as before; use TestDisk (Ultimate Boot CD has this) & let it recover whatever partitions exist; rewrite bootloader with the OS CD (assuming its Vista/2008/7). Original & Intel forum threads.
3. My answer: assuming you tried step #2, reload Windows using a newer Intel Rapid Storage Driver and then with only a minimal setup, recover the necessary data with Partition Recovery software from DiskInternals (costs $200 for business use, but cheaper than forensics).