HD Icon missing in Finder and Disk Utility, but shows up on System Profiler

[Hombre]

Hello...thank you in advance for your response!

I left my Mac Pro on overnight to download a large file to find out in the morning there had been a power outage at some point.

The HD that was running at the time no longer has a desktop icon, nor does System Prefs/Startup Disk or Disk Utility recognize it as existing, although it DOES show up in the System Profiler....obviously I can't boot into the drive at this point.

I have ALREADY TRIED:
1. Checking Finder Preferences to make sure Hard Drives etc are being shown. They are.
2. Left clicking the finder window and choosing 'Clean Up' to refresh the window.
3. Restarting several times
4. Trying the Finder menu: GO>Go to Folder> and typing in /Volumes
5. Trashing the file: com.apple.Finder.plist from GO>Home>Library, and restarting

NONE of those has worked.

I HAVE Disk Warrior, which does NOT show it as in it's Home menu, but DOES recognize it as existing within it's hardware check, and notes that it is functioning properly, but because it does not show up in the home menu, I cannot access it to rebuild whatever has been corrupted etc.

Does anyone know how to deal with this?

 

[DeltaMac]

Is that missing hard drive one that you use for file storage/backup?
Does it have an OS X system installed on it, that you could use to boot your Mac?

Obviously, it's not the hard drive volume that you are using to boot from, because you wouldn't be able to restart at all.

How many hard drives are installed internally in your MacPro? Is that missing hard drive an internal one, or is it attached through USB or Firewire - or is it a network drive?

Is this a volume that does not appear? or a hard drive?
That is, do you see the hard drive, but not the volume in Disk Utility? The hard drive may appear as a device (and show the manufacturer's data on one line) and any volumes on the hard drive would appear underneath it.

If the hard drive is an internal one, and there's hard drives in all slots, you could try swapping the hard drives between slots. It only takes a few seconds to try that. Start up your Mac, and check for that drive again.
It the drive is in an external case, you could try the drive in a different case - or remove from the case, and try it out in one of the internal MacPro drive slots.
Finally - do you hear the hard drive spin up when power is turned on? Probably the best way to do that is to put it in an external case or drive dock.
That last question assumes a spinning hard drive - an SSD would be silent, of course.