ITunes Sync Has Deleted All Music Off IPod

Fist off hello to everyone. I hope you can help.

On a mates computer he had all of his music in his ITunes Library and when his IPod was connected it was set to auto sync with ITunes library.
His flat mate then bought a IPod and connected it to ITunes.

My mate complained that when he clicked on a song in ITunes it didn’t play. When I looked at it I realised that music ha been deleted from its location on the computer. I checked the settings in ITunes and wet to the location on the computer and sure enough his music was nowhere to be seen just new songs of his mates. I checked the recycle bin and it wasn’t there either.

I then decided to copy the music from the IPod back into ITunes. So I deleted all of the duff music in ITunes so it was empty. I adjusted the settings of the IPod in ‘My Computer’ to show the hidden files and then went into ITunes to adjust those settings and import the stuff from the IPod.

To my horror all of the music got deleted off my IPod. I assume as it was set up to sync it deleted the music.

I ran Recuva to see if I could get the music back deleted off ‘My Computer but no joy.

Any advice or software recommendation would be very much appreciated.

Thanks.