Plugged in old iPhone (to use as an iTouch) none of my new music....

Question

None of my new music switched over and now it acts as if my old iPhone is my default iPhone. My current iPhone that I have used to purchase songs on, will not transfer any of those new songs over to my iTunes library.
Basically everything was operating fine, I wanted to sync my current library to an old iPhone (to use that phone like a Touch)...once plugged in to sync old iPhone wanted to take over and sync the songs on that iPhone onto my library and basically delete any songs not loaded into that old iPhone out of my library.
But the big issue is now when I plug my current working iPhone into my iTunes library it doesn't recognize that phone and wants to delete any purchased songs (via the iPhone) off that iPhone and install an older library onto that iPhone.
I will probably end up loosing about $75 in downloaded music purchased via my phone (shame on my for not syncing it more often).
Hopefully you can understand that? ANY help is greatly appreciated!!!!

Answer 1

These are two possible approaches that will normally work to move an existing library to a new computer.
Method 1
Backup the library with this User Tip.
Deauthorize the old computer if you no longer want to access protected content on it.
Restore the backup to your new computer using the same tool used to back it up.
Keep your backup up-to-date in future.
Method 2
Connect the two computers to the same network. Share your <User's Music> folder from the old computer and copy the entire iTunes library folder into the <User's Music> folder on the new one. Again, deauthorize the old computer if no longer required.
Both methods should give the new computer a working clone of the library that was on the old one. As far as iTunes is concerned this is still the "home" library for your devices so you shouldn't have any issues with iTunes wanting to erase and reload.
I'd recommend method 1 since it establishes an ongoing backup for your library.
Note if you have iOS devices and haven't moved your contacts and calendar items across then you should create one dummy entry of each in your new profile and iTunes should  merge the existing data from the device.
If your media folder has been split out from the main iTunes folder you may need to do some preparatory work to make it easier to move. See make a split library portable.
Should you be in the unfortunate position where you are no longer able to access your original library or a backup then then see Recover your iTunes library from your iPod or iOS device for advice on how to set up your devices with a new library with the maximum preservation of data.
tt2