Question : iTunes playlist gone but music library intact, how to recreate from iphone

I have latest iTunes on a PC w Windows 7 and all of a sudden my playlists disappeared and were replaced with the default ones.  All my music files are intact.  I understand there is an iTunes Music Library.xml file and I found that it supports the lost of the playlists.  I tried uninstalling and reinstalling itunes.

My iPhone has all its playlists and music intact from previous sync. My question is this:  If I sync my iPhone now will it reestablish those original playlists back on my PC?

Answer : iTunes playlist gone but music library intact, how to recreate from iphone

No, it will do the opposite: It will obliterate the custom playlists on the iphone, and replace them with the default playlists from the PC.  By and large, iTunes "syncs" music and related lists one way only: from the PC to the phone.  (The exception is that it will copy music you bought on the phone at the iTunes store to the PC).

You could transfer the playlists on the iPhone to the PC using the free software "Sharepod".  Very easy to use:  http://www.sharepod.com