ITunes syncs to the iPod, iPad & iPhone.
It is a one way sync. During the sync it will compare what is on the device to what you have in your iTunes library.
Because you do not have any music in your library, the external drive which houses the music is not visible, iTunes goes ahead and syncs NO music. In doing so, it make the device hold exactly what your iTunes library holds, Nothing!
I'm a little surprised that iTunes actually launches and allows a sync while not connected to a library. I suspect that there is another iTunes library inside your music folder on your computer. This is the library that iTunes is using when it syncs the device. Of course, it's empty.
Basically, the solution is very simple. Connect the external drive when syncing your device.
Greetings. This is kind of a stupid problem. Either the soution will be very simple or there is no solution. Here are the details: I have my music on an external HD and when it's not in use I have it unplugged. A week ago I got an new iphone and synced huge amounts of music to it. Then I glibly unplugged my HD. The next sync removed it all. Like I said -- stupid. I looked through the available itunes settings but I'm not really sure if they will handle the issue. Like the setting for "manual management" of my music. Is there any way to set itunes so that it will sync my other content without deleting my music when the HD is not plugged in? Many thanks for your thoughts. GL