SSD root file system broken, recover?

[Thomas Kaiser]

Hi

I have Ubuntu 12.04 installed on a SSD. /root on the SSD, /home and /var 
on the HDD. Today, the SSD (root) stopped working.

For a fast recovery, I installed Ubuntu 12.04 again on free space on the 
HDD. Edited fstab to point to the old /home and /var.
Things looked normal after that, but all the additional software I 
installed is missing.

All the .dep files form the updates (and application installs) I made 
are still in /var/.... So, I assumed that launching the update manager 
will reinstall the missing parts which were already downloaded and 
available in /var. The update manager just told me the system is up to 
date, but it's not.

What is the right way to get update-manager or apt to re-install the old 
applications?

Or the other way around:
I installed the system files on a separate partition (HDD). How to get 
the system files and all installed and updated applications back after 
the system partition (HDD) crashed?

Thomas

PS: I keep backups from home and /etc.