How do I recreate the file /var/lib/dpkg/available ?

[Klaus Ade Johnstad <klaus@astro.uio.no>]

I "accidentally" deleted the files /var/lib/dpkg/available and 
/var/lib/dpkg/available.old (they were huge), now I need to recreate them 
again, becasue I can't install anything without them, even 'dpkg -l' turns up 
with nothing. I've looked into the different man pages of dpkg and  apt, but 
haven't found a solution.

klaus