I started gtk-gnutella without network connenction
 

I started accidently my computer without being connected to the internet. When I launched gtk-gnutella the tabs "active downloads" and "queu" were empty.

When I'm connected to the internet those tabs don't list previous downloads, although they are still in my /incomplete directory.

Is there a way to recover those incomplete downloads?

If you search for the files again, it should be able to find sources for them and resume the downloads.