Lost 2nd hard drive?

I have a 2nd hard drive installed on my G5 that I mainly use as a backup, but also have a bunch of media on it that I brought over from my old system. The problem is that I just noticed the icon for it is missing from the desktop and it is no longer in the main Finder menu either.

Anyway, I found it (or what was it) in the Disk Utility and the name seems to have been changed to "disk0s3" and it says it's 'not mounted'. I used the verify button and it came up error and said it needs repair, so I tried repair and it said it could not be repaired because of an error. Now I don't know what to try next to get it back (it was there last week). Is it possible that it could have been accidentally ejected off the desktop?

Most of what is on it is backed up on CD and/or my main drive, but I'd still like to get it back working again.

Fwiw, I'm using 10.4 Any suggestions appreciated.

Is it SATA or external? You can't eject Internal SATA.

Well,... Apple says that if disk utility can't solve your problems, try a third party utility like TechTool Pro 4.

Unless the disk is shot. You should at least be able to initialize it w/ TT4.

It's SATA.

I also just noticed that whenever I restart the system now I get a little warning window that says:

"! Disk Insertion
the disk you inserted was not readable by this computer"

With three buttons marked "Initialize", "Ignore", and "Eject".

I've tried pressing all three and the window goes away, but does nothing else. (No, there is nothing in the optical drive)

I also tried physically unplugging the HDD, plugging it back in before startup to see if I could at least get something to appear on the desktop, but nothing does.

Seems odd since I hardly ever use this drive, but I always thought it read too slow and have considered replacing it for that reason, but it didn't make noise or anything.

Oh well, if it died, at least it's not the boot drive.

update: after doing a bunch of restarts while trying to get a 3rd party disk utility I downloaded working, the drive re-appeared out of nowhere, exactly how it had been. Too weird.

Needless to say, I quickly drug everything on it to the main drive that wasn't already there.

I think I'll be replacing that one....