iTunes library erased - restore it from my iPod Touch?

the following post by Zevoneer in this thread http://discussions.apple.com/message.jspa?messageID=8794716 says it all:

Did you back up your purchases before you you reinstalled your system? If you erased your drive then the purchases will have been erased along with everything else. If you didn't make a back-up of your purchases to restore from (as you are advised to do) then I'm sorry to say that the policy on lost purchases is that you have to pay to download them again:
"Once a Product is purchased and you receive the Product, it is your responsibility not to lose, destroy, or damage the Product, and Apple shall be without liability to you in the event of any loss, destruction, or damage." iTunes Store: Purchased content can be downloaded only once

You could try contacting the iTunes Music Store Customer Service and you might be able to persuade them to sanction a second free download. There have been occasional reports in the iTunes forum of this happening, however just be aware that they are not under any obligation to do so. If you click on this link you'll be able to email your query: iTMS Customer Service

If you have an iPod that still has the purchases on it the transfer of purchased content from the iPod to authorised computers was introduced with iTunes 7. You'll find details in this article: Copying iTunes Store purchases from your iPod or iPhone to a computer

You might also want to check out these pages for future reference:
How to back up your media in iTunes
Back up your iTunes library by copying to an external hard drive

good luck !

J GG

*Many articles have told me how to look for the "hidden file" called iPod_control and to copy it into "My Music."*

The articles you are looking at were designed for iPods that can be enabled for disc use (iPod Classic, iPod Nano, iPod shuffle), not for the iPod Touch.

There are a number of third party utilities that you can use to retrieve the music files and playlists from your iPod Touch or iPhone. You'll find that they have varying degrees of functionality and some will transfer data (such as playcounts and ratings), movies, videos, photos, podcasts and games as well.

A selection of iPod/iPhone to iTunes utilities:
Senuti Mac Only (iPod Touch & iPhone compatible)
SharePod Windows Only (iPhone and iPod Touch compatible)
TuneJack Windows Only (iPhone and iPod Touch compatible)
iPodRip Mac & Windows (iPhone and iPod Touch compatible)
Music Rescue Mac & Windows (iPhone and iPod Touch compatible)
iPod Music Liberator Mac & Windows (iPhone and iPod Touch compatible)
iGadget Mac & Windows (iPhone and iPod Touch compatible)
iRepo Mac & Windows (iPhone and iPod Touch compatible)
iPod Access Mac & Windows (iPhone and iPod Touch compatible)
TouchCopy Mac & Windows (iPhone and iPod Touch compatible)

Purchased applications can be downloaded over again, see this article for details: How to redownload purchased applications from the App Store

One last thing, if your iPod is set to sync automatically you need to take care connecting to an empty iTunes. Open iTunes first and go to Edit>Preferences>Devices and check the box "Prevent iPods and iPhones from syncing automatically" and choose Ok before connecting your device.