It happened to me that while upgrading to Ubuntu 12.04, I made instead
aptitude dist upgrade. I downloaded the ISO version for a from-zero installation. In the partition definition I choosed that my home partition to remain as my home, but I assumed wrongly that if I choose ext4 instead ext3, a reformat would happen without losing my data.
The installation completed 'successfully', except that I lost 100 GB of my precious music collection, documents and so on.
Is there a way to recover my life (my music), considering that I have not done anything over disk after installation?