New iTunes 12.3 update has me confused?

It's erased all my legally bought and imported CDs, can I get them back? And why when I try to sync my iPhone does it say it's on a different library when I've only used the one laptop for iTunes? How can I fix that so I can sync music again?

ITunes was never an easy prorgram to work with.

  • What is iOS 7? A new iphone or a new software update? So is iOS 7 a new iPhone coming out or a new software coming up? And when is it coming out? And if its just a software update when is the next iPhone coming out?
  • Upgrading from S3 to iPhone 5? Confused about the new T-Mobile system? I've had the Samsung Galaxy 3 for around 7 months now, and I want to upgrade to the new iPhone 5. I have a family plan with 5 people including myself. Originally, I had a two year contract with my S3 but I planned on giving it to my brother while I would get the new iPhone. What are all the fees and how exactly can I upgrade?
  • New iOS 6 update, find my iPhone update? I don't like the new find my iPhone update is there a way to change back to the old find my iPhone but keep the new update? It's not showing locations like it used to and won't even how me major boroughs like Croydon. Streets are difficult to see, much smaller picture. General *** compared to the older version.
  • ITunes has deleted half of my new album? Yesterday I purchased a music album using the iTunes app on the iPhone. This morning I plugged my phone into my computer to do something and I find that it has taken 8 of the 15 songs out of my iTunes library. When I go into purchases it tells me that I have only downloaded half of the album… How can I restore my other songs?