Why has Hudson appeared to delete all of my jobs after an update?

I have am running Hudson on Ubuntu in a VM, and had a couple of jobs configured.

I have just installed the latest updates through Ubuntu's update manager, which included a new version of Hudson.

However, after rebooting and viewing Hudson, it appears that my jobs have been lost - they don't show up in the Hudson UI, and I can't find them on disk either (they were in /var/lib/hudson/jobs).

Any idea if these are recoverable?

From stackoverflow

• Under where Hudson is installed, there should be a directory called WEB-INF. In that, there is a file called web.xml

  Edit that. Look for HUDSON_HOME. Change the value to point to wherever it is you had your HUDSON HOME directory (where your workspace is, etc).

  You should have your jobs back. I face this issue every time I upgrade, but in my case it is caused by the fact that I use Tomcat.