Import music into iPhone without deleting everything My OSX crashed and I installed it completely new (no backup). Now I wanted to import some music into my iPhone and it seems it is not possible. Every time I get the warning that everything get deleted if I synchronize it with iTunes. If I want to manage the music/video manually I also get this message. What can I do? The data on my iPhone should stay. I only want to add something ...

PS: Does it mean that my backup made with iTunes will not work?
If you never synced the iPhone with your PC/Mac, you cannot manually add songs without first deleting the iPhone (I am 99% sure about this). 

You can use third party iTunes alternatives (i.e. CopyTrans Manager for PC and Sharepod for Mac to add songs to the iPhone without the need to sync with iTunes.