=> cp /etc/apt/sources.list /opt/sources.list.orig
=> Change following settings in /etc/apt/sources.list
deb http://old-releases.ubuntu.com/ubuntu natty main
deb http://old-releases.ubuntu.com/ubuntu natty main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu natty-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu natty-security main restricted universe multiverse
=> apt-get update
=> mv /var/lib/apt/lists /opt/lists.orig
=> mkdir -p /var/lib/apt/lists/partial
=> apt-get update
=> cd /var/cache/apt/archives
=> tar -cvf /opt/archives.tar *.deb
=> apt-get clean
=> apt-get install default-jre --no-install-recommends
NOTE :- In my case packages were just downloaded but not installed. so in such case do as following:-
=> cd /var/cache/apt/archives
=> dpkg -i *.deb
