ALL of my playlists, folders and half of the music files are gone

Question

I've reinstalled my Mac OS, before that i moved my iTunes folder to external hard drive. Also exported the iTunes Music Library.xml file, because i've read that it keeps all the data connected with playlist and folders.
I had more than 200 gb of music, all sorted by myself by artist and genres folders (so you can imagine how much time did it take)
Now I have installed Lion , i tried to copy all files from iTunes folder which is based on an external hard drive, but none of folders or playlists appeared and only 130 gb of music files has been copied to the application.
Please help, that was really important for me, i'm just crushed. And sorry for bad english btw.

Answer 1

You say you moved the iTunes folder but you also specifically mention copying the .xml file which makes me wonder if you really did copy the whole of the iTunes folder and all of its contents.  If you had, there would have been no need to mention copying the .xml file because it is inside the iTunes folder and would be copied along with everything else.  What I am getting at is, you either didn't copy everything you need, or you haven't restored it correctly.  Here's the correct way if you let iTunes manage your music:
iTunes: How to move your music to a new computer [or another drive] - http://support.apple.com/kb/HT4527
do not confuse moving your whole folder and library with moving just media files as in
iTunes for Mac: Moving your iTunes Media folder - http://support.apple.com/kb/HT1449
Quick answer if you let iTunes manage your music:  Copy the whole iTunes folder and all its subfolders and files intact to the other drive.  Start iTunes with the option key held down and guide it to the new location of the library.
Putting iTunes back onto the computer is the reverse.  Just copy the iTunes folder to you Home > Music folder and start iTunes (it will automatically look in this default location unless you hold down the option key while starting).
By the way, while the .xml file also contains the library information, it isn't the file that is actually used by iTunes.  The really critical file in iTunes is the Library.itl file which is also in the iTunes folder.