Why did my itunes delete all the music off my iphone and how do I get it back on? Syncing has not worked

Got my Iphone. Already had itunes and was able to figure out how to put my music on. Got a new laptop with Windows 8. Downloaded itunes and authorized this new computer. Imported a cd to the library, then couldn't sync the new songs from the cd. Somehow started a sync, then boom all the music was gone from the iphone. Maybe I hit a restore button? Don't have a clue what I am doing, now I have managed to get only the imported songs from the library onto the iphone, but none of the others. Everytime I plug it into my laptop, my photo stream asks if I want to download all my pics, that are already downloaded, and doesn't open itunes. Help. I am getting fed up and cant even figure out how to download the user manuals on any of this stuff!