Itunes ?

I was originally unable to find the disc in finder. I did all the things you mentioned. When i checked the box on usb in finder, i was then able to see the hard drive. { i labeled it "music", btw}.

When i ran disc utility, it said it couldn't be repaired or something similar.

What happens if you try to look at the files that are on it?

If you are able "to see the hard drive" it tells me that it probably has not experienced a hardware breakdown. So the problem may be a file system corruption, or something like that. The FAT32 file system is prone to that, and external drives are often supplied formatted in FAT32, because that file system can be utilized by both Mac and Windows machines.

I again suggest that if you can get access to a Windows machine, you connect the drive to that machine; examine its "Properties," which among other things will indicate "FAT32" if that is its file system; see what files are indicated as present, if any; and if the music files are not indicated as being present run ChkDsk on the drive. Post back if you'd like further information on how to do that, indicating whether the machine has Windows XP or Vista or 7.

Regards,
-- Al

Update,
I hooked the hard drive with my music back up to do all the steps that Tobias mentioned. For some reason, i was able to play music on itunes now.
It gives the alert that Start up disc is almost full.

When i went to do a disc repair on my hard drive it stops with the message "first aid failed".
Most of the music plays on itunes without the hd attached but a few say file not found. When i hook up the hd, all the files will play. This has me thinking that most of the music is on the internal hard drive., and i have duplicated them on the hard drive.
How can i erase the internal hard drive of all this music and free up space, while using the hd for keeping music only.

'

to get it all on the external drive first go to advanced preferences and make the external drive your iTunes media folder, if you click change you can browse to it.

then go to File - library - organize library and then choose consolidate. It will copy all music files not already there to that drive. Make a backup copy of the music drive and then delete them from the internal drive.

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Streetdaddy, the "first aid failed" message may be because of the circumstance Al posted on above: FAT32 formatting of the hard drive.

If that's the case, I certainly agree with Al that you have much to gain by correcting the situation. Transfer your music to a backup drive when you have finished following Herman's suggestions, above. Then partition the hard drive as I described in my own long post, using Disk Utility. Finally you recopy your music to the reformatted drive.

Use SuperDuper ( or Carbon Copy Cloner ) to do the first transfer and the second recopy. Just clone one disk to the other.

Once that's done, you may have to tell iTunes once more, via Preferences --> Advanced ( thank you Herman ) where your iTunes Media folder is.

Good luck and update us if you can.

OK, i renamed the itunes library, consolidated files. Then went to back up the main Drive, but it said unable to run because memory was full. I then took both drives downstairs to my imac and tried to make a backup using superduper.
When i tried to select the drive to be copied, it didn't show up as an option.
I could see the backup drive, but not the main music disc. They were both mounted ( you like that? see, i learned something,haha) on the desktop,tho.
Just by chance when i looked thru the to be copied to options, there was the main music drive as an option. When i clicked it, it said "music" is not a mac formatted disc. it is formatted in MS DOS .To use it i would need to erase it using disc utility and reformat in mac os extended.
So do i need to copy the main music disc to my internal drive and make the copy from there? Don't know if i have room...there are 4000 songs on there in Apple Losseless. Thanks again for the patience !