After switched to my new iPhone all of my purchased music from iTunes disappeared

I cracked the screen on my first iphone 4s, and when I got a new phone to replace it, HALF of the music I had purchaced VIA ITUNES is gone. When I got my new iphone the lady who "activated" my new phone accidentally backed up what was on my itouch instead of what was on my old iphone, so I started over with my contacts & pictures ect. Did this screw everything up? I would think itunes would have record of music that I had purchaed somewhere on itunes, but I've looked everywhere & it is nowhere to be found. In fact, the entire "purchased" playlist on my iphone has vanished. Any ideas on what I can do to resolve this problem? around 50 purchaed songs missing.