Most people make a regular backup of everything they really really might need some time later, just to protect themselves from disk crashes, accidental deletes and overwrites, virus damage, files corrupted by program errors and things like that.
Not really difficult to copy data to an external hard disk, nowadays, as a basic precaution.
Those that don't risk losing data, as you noticed.
I recently formatted a partition of my NTFS drive using windows xp setup and reinstalled XP Pro and all my software. What I failed to do was backup all my emails from Mozilla thunderbird and I really really need them. Through windows setup, I deleted the system partition, created a new one in its place and formatted it (slow format), and then reinstalled XP Pro and all my software.
I've tried using "Recover My Files" and "Get Data Back" but all it seems to recover are newly created files...no matter which mode I use.
Is all hope lost for my emails or is there some way I can still retrieve them?