There are many data recovery programs, some of them very good, but sometimes just isn't possible to recover. Worth trying though, if there's no backup.
Preventing data loss is still the way to go. After all we have a huge amount of data these days, and they just get larger in time; and they need to be maintained by "copy over to another place" to refresh the written sectors on the disks. Having multiple copies is even better, and if they are kept far from each other, the chance that one copy survives is even higher, maybe using online backup services in this case.
