Syncing, Itouch library with Itunes linbrary

My Computer had a virus and everything needed to be reworked.... My pictures and iTunes libraries were saved. Here's my dilemma.

The "new" iTunes library that I have now is an older that my most recent library ( newer songs / etc) My iPhone is synced to this library. I manage what music is shared onto my phone. my iTouch and iPod has the most recent library with new songs, and organized playlists etc.... I want to sync all my devices to my iTunes library without losing all 4000+ songs. on my iPod alone, i have 4858 songs.... and on my current iTunes library I have around 1000.

how do i sync all devices to iTunes without losing anything ?