ITunes :: How To Recover Music And Apps Already Bought From Store

I wonder how I can recover the music and Apps that I already bought from iTunes store.�I lost my iPod and I want to check for the music and the Apps I bought since I am thinking in buying a new iPod, but there are not in my iTunes.�I tried all I could try to get them back but nothing.�I check the list of the thing I bought from Apple Store through iTunes and some of the music and Apps are in the list, couldn't find how to downloads again, but not all the music or Apps were there.

Info:
MacBook Pro (15-inch Mid 2009), Mac OS X (10.6.8), iTunes version 10.6.3