External Hard drive Drama!

Hello, first post so please excuse any errors I'm making...

I have an old iomega 250 gig hard drive that has been working fine for years, and came ready to use for Mac. The other day I wanted to transfer some files off the hard drive to a friends Vista Computer. Well as soon as I plugged it into his computer, it started installing drive updates for my iomega drive. I let it finish, but realized the drive wasn't showing up on his windows menu so I unplugged it and took it back. When I plugged it back into my computer I got the "The disk you inserted is not readable by this computer" error message, and when I bring up disk utility, it shows the original disk description "250G ST325082". It doesn't give me the option to repair, and I'm worried I may have lost all the data. It says the partition map is unformatted if that matters too.

Is there any way I can save the data that was on the harddrive? I foolishly never backed it up, but I'm almost positive this is b/c of the drive update and not a mechanical failure, which gives me some hope.

Thanks!

Do you know what kind of updates Windows installed to the iOmega? I don't understand why it would install updates unless it was offering to install a firmware update.

What I think may have happened is Windows re-initialized your iOmega drive. Which means that it could have wiped the partition table and reformatted the drive. If that happened it's bad news because your data is gone.