All of my songs in iTunes are now gone

Hello,
I keep all of my music files on a mybook external hard drive. For some reason, every time I restart my iMac the volume name for the mybook changes

for example: mybook (restart iMac) and it becomes mybook 1 and then mybook 2 and so on

iTunes actually seems to be the only application that notices and renames the default location. For everything else, I have to go in and update the #. When iTunes last upgraded, it asked me about updated the folder. I said yes and half of my songs disappeared . I didnt notice for a week because all of the new songs I was imported were there, but when I went to look at my playlist, all of my older songs are gone. Not the ! where I have to go relocate. They are gone.

I did a little reading on the net and tried multiple things as far as trying to get iTunes to reindex the iTunes music folder. I even deleted the xml file - oh yeah that's where all songs disappeared.

So, how can I get the songs in my iTunes folder indexed again by iTunes.

Thanks in advance,