To enable you to recover the data, youll need to have the necessary hardware.
1. A NAS or spare PC with significantly large network storage share.
Reason: an equal amount of space available somewhere else. If you had 3 x 1TB disks in RAID 5, you will need at least 3TB storage elsewhere. Likewise, if you had 5 x 3TB drives, youll need 15TB storage available on the network. This How To assumes you have a NAS with enough spare storage available, and is accessible on the network and ready for writing. Ka-ching!
2. An alternative disk connection. This can be a spare PC with spare disk ports, or an external HDD mount. This How To assumes you use a USB HDD dock
Reason: Since the RAID controller is the interface between your OS and the disks, your OS can only see the corrupted RAID, and may not even see the individual disks depending on the RAID corruption. Your disks will need to be removed from the existing controller and attached via an alternate means to a bootable Windows OS. If youre plugging them into a different PC, ensure the disk controller isnt the same model as the one controlling your failed RAID (which basically means ensure its a significantly different motherboard model). An external USB3 HDD dock is a safe bet, and not too expensive.
3. UPS me up, Scotty!
Reason: Youll need enough UPSs for all components during recovery. It/they need to be able to power a PC, a NAS, a switch/router and a USB HDD Dock in the event of a decent power failure. You know itll happen during this process (damn you elder gods!) so best protect against it.
4. R-Studio Network Edition. Prepare to buy it, but not yet. Get the trial for now.
site: http://www.r-tt.com/
download: http://www.data-recovery-software.net/Data_Recovery_Download.shtml
store: https://secure.r-tt.com/cgi-bin/Store?id=1
Reason: Its the most stable, assured, and fastest RAID reconstruction/recovery tool Ive encountered (from recent experience, Jan 2013). There are other tools such as Zero Assumption Recovery that will probably suffice, but my personal recommendation is R-Studio. Since this How-To assumes youre recovering to and from a NAS or network share, the Network Edition is required. If you have uber space locally, the standard version is fine.
If you make it through to seeing your files later in this process, youll need to then purchase R-Studio, but in the meantime just download the trial. Install it.
5. ReclaiMe Free RAID Recovery
site: http://www.freeraidrecovery.com/
download: http://www.freeraidrecovery.com/download.aspx
Reason: This automates finding the correct parameters for reconstructing a virtual RAID, and gives clear and concise R-studio instructions when finished. And its free! If youre handy with a hex editor, you can ignore this program and follow the R-Studio tutorials on finding RAID parameters (http://www.r-tt.com/Articles/Finding_RAID_parameters/). This How To assumes youre using this program, so install it.