I am running Ubuntu 12.04 LTS. I set my system to back up a few key folders (including Thunderbird) to Ubuntu One daily. A few days ago, all the data in my calendar in Thunderbird disappeared (including a great many doctor appointments). It has taken me three days of fooling with the 'login keyring" but I finally was able to login to Ubuntu One, only to find that it is empty.
Can someone explain to me how this happened and especially if there is any way to recover the files that I thought that I was backing up?