I deleted the content folder which I exported from RB to my usb-stick. Now I cant rebuild it.

Hi,
I deleted the content folder on my stick which came by exporting tracks from RB to my usb-stick. Now if I export those files to my stick again, nothing arrives there. I tried to copy and paste the single artis/release/track - folders manually, but they dont work on my playlist now. how can I make them work on my playlist?
Maybe there´s a way to delete all data concerning those tracks so I can delete and export them to the stick again?