Ok so we recently had to switch iTunes from one computer to another. for some reason there were hundreds of songs lost in the transfer and are no where on either computer. I have all the music on my iPod and i thought it would just transfer it to the computer when i hooked it up. But it keeps saying that all existing songs on my ipod will be replaced with existing songs on my computer. how do i transfer the music from my iphone to my computer without it deleting anything?