playlists appear in itunes but not on iphone

Hi
I have an iPhone 3G running on 4.2.1 and iTunes 10. My hubby has been screwing around with the library (am really not sure what he has done) and now when I plug in the phone the playlists that appear on the iTunes music list (I have about 40 self-generated lists) cannot be seen under the music tab of my device. So I cant check the playlists I want to synch. They were there before and they are still all there in iTunes but since I have synched after his fiddling I have lost all but the standard playlists off my phone. Have been going nuts as this is how I narrow down my songs from a 10,000+ library. Anyone got any clues?
iPhone 3G 16mb Windows 7