Need help, hdd missing!

I have a Power Mac G4 Gigabit Ethernet machine with dual 500 mhz processors running 10.4.11. It is set up with an administrator account and two other accounts. Yesterday I went into the permissions of my external usb hard drive to disable the other two user accounts from accessing it (so I thought) by right clicking and going to the get info screen. Well, now the drive doesn't mount at all, I've tried disk utility and tech tool 4 to no avail. It doesn't even show up on either one and I can't use the mount command in disk utility. Can someone please please help me get my external drive back? I have a lot of work and family related information I need to access. Any suggestions will greatly be appreciated!

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What else did you do when you accessed the get info screen?

- Simon

Helps if you provide the OS details, however boot from your install disk by holding down 'C', go to Utilities in the Menu Bar and run Repair Disk from there and advise what is reported. The drive may have expired alas!

That is all I did that I can remember from the get info screen. I tried booting from the install disk (I am running 10.4.11) and disk utilities still did not find the drive. This really has me puzzled, I tried connecting the drive from the usb hub to direct ports on the monitor and then to ports on the mac itself with no luck. Nothing I can think of is helping, and I wish I knew of some way to pull up the get info menu again for that drive so I could undo what I did.