Other Managing large iPhone music library with missing songs on PC

I have a sizable music collection on my iPhone which is synced to iTunes. The problem is that I lost external drive with library and now when I try to sync it to remove some songs it does not actually do it. Part of the problem is that I skip songs I don't like so using play count I was planning to delete songs I don't like. At this point I am willing to try a software to extract songs from Iphone. This is Iphone 4 with old firmware so can be jailbroken if necessary. Any suggestions?