Nervous breakdown after iphone?

I think I'm having a nervous breakdown! I lost 500 songs off my iphone when I was sync them onto iTunes. I can't really breathe right now!

Hi, click the backup button on itunes and you will be fine.

With my experience on ITunes, say I bought a song years ago for my iPod, but never synced it to my IPhone, and hit to buy it again on it it should come up saying you already purchased this, do you want to either purchase/download it again? Hit yes and I'm pretty sure it doesn't charge you. You just need to try and remember the exact songs you bought since some songs have many variations.

Well you have literally just made me wet myself:/