Upgraded iTunes and lost apps, playlists, and songs

I recently had to update my version of iTunes so I could update my iphone. A week or so after I did this I went onto iTunes and it looked different, all my apps were gone, my playlists were gone, and I lost all songs after 2010. I had a playlist for each of my family members ipods and a seperate one for my phone as my phone doesn't hold much. When I plug one of them in it says if I try to sync it will lose the stuff on the devices. I was reluctant to do this in the first place as this happened to me years ago with an update. I have since done it a few more times with no issues. But in order to update my phone it said I had to. I have about had it with apple products and hearing things that happen to others information and losing it all. I am tired of the constant asking for updates and upgrades. If there is anyone that could help me I would appreciate it.