Some Hard Drives Cannot Be Recovered

In spite of the hype from some of those those deeply involved in the industry, data recovery is in fact not always possible. Some companies claim 99.9% recovery rates, but this is not credible. Hard drives store data on metal discs that are a little smaller than DVDs. They are so finely polished that they reflect like mirrors. Disk drives are designed such that the heads that read the data do not touch the surface – they float above the disc surface to prevent any damage from friction. So what happens when you get a dreaded head crash?
These flying heads bounce uncontrollably off the surface, scraping away the magnetic substrate which holds the data at over seven thousand revolutions per second. I have seen the results of some of these – the metal discs are no longer perfect but have crude rings cut into them. Such damage means that the data cannot be recovered regardless of what any recovery company may tell you.