yeah, don't reformat....take a step back...clear you head...walk around the block...
Now, what happened? Your BIOS got reset...ok...first fix the bois. Make sure that it's working properly and it's set for RAID not AHCI or something. If it went back to default status, you need to reset everything to the way it was. Personally, I would do a full reset on the bios at the board level (jumpers) and then start again with setting it up for your RAID. I would remove any non critical path items from the board, USB etc. Take out all but one stick of memory. The idea is to take this down to the simplest configuration first.
Take another deep breath...step away...walk around...come back and double check your setting and the rig setup...cables everything. Reconnect drive cables or check that they are secure...
Ok...now boot...
Go into the RAID settings...make sure that they are setup correctly. You didn't say what Chipset or even if you were using chipset raid, but I'm guessing Intel. Go into the intel setup at the BIOS level and see that your RAID sets are still listed as valid and your drives are shown there as good. It should show a valid RAID config. This information is stored on the drive itself in a few places, so it's unlikely that it would be corrupted. If you formatted the drive and did a low-level wipe, it would be gone, but I'm guessing that you didn't do that and the power spike wouldn't do that.
Try to boot. You didn't say if this is the boot volume, but with that size, I'm guessing that it isn't a boot volume.
you should boot up.
go into you control panel and check the disk partitions. If you are showing multiple disks and not a single raid volume...then you have an issue. It's like a chipset issue...that's my guess. Don't mess with the drives like formatting them.
If you show one big drive, then RAID is working and now we need to check the file system.
The fact that you are saying one of your drives has no data on it tells me that you are seeing more than one volume, which means RAID isn't working...that's chipset.
What RAID level?
What Chipset?
How many drives?
Is this the Boot volume?
What OS?
please, don't rush anything...I see that you are a lifer and probably know all of the above, but I can't tell you how many times I've gotten frustrated and done something horribly wrong in the heat of passion.
keep us posted.