There are two types of computer users - Those who have lost data and those who will loose data. To change your membership from Group A to Group B is only a matter of planning (or the lack thereof), good (or bad) luck, and a matter of timing. What I mean by timing is .... did the backup drive fail with the only instance of the saved data because it was part a flawed shipment of drives (you get the picture).
Over the years, clients have frantically called with a similiar tale of woe - "I turned my computer on this __________ (morning, afternoon, evening, week, month,etc. - You choose the time interval) and I saw a blue screen. Oh, I say, you received a BSOD. A BSOD? What is that? I then said, " That's the Blue Screen of ..... DEATH! You would then hear a long pause, sometimes followed by a loud thud. In the background, a faint voice would cry out, "Get the smelling salts".
After calming down the client (author's note - the status of the client's unpaid invoices will have direct impact on the time interval prior to the client being put at ease and the success of the recovery) ; I then explained the details. Windows, unfortunately, has a tendency to self-destruct. The Windows registry file is the most critical file in a Windows installation. Specifically, the registry is the database in which the operating system stores most of its settings. The installed programs and hardware store their settings within this file. Importantly, the registry defines relationships between different parts of the operating system's user interface. For example, the registry defines what you see on the desktop; how the Start menu and taskbar work; and how the operating system starts. So, if the registry file becomes corrupted then Windows will not start and the computer bootup will result in the dreaded BSOD.
However, the critical personal data files are still recoverable. The use of a self-booting CD with Windows PE allows you to look at the file structure on the hard drive, find the data files and save the information to a removable flash drive. Whoa, cowboy. Try explaining this in english. Ok. I'll slow down and use non-geeky terminology.
Windows PE (or Pre-Installed Environment) is a bootable CD that allows the user to boot up an otherwise non-bootable computer and provides you with a complete complete Win32 graphical interface (point and click ) with network support, a graphical user interface (800x600) and file system support. It allows the user to save files to a removable flash drive or to a network shared drive. I personally prefer to use Bart PE ( http://www.nu2.nu/pebuilder/ ) which is a Windows PE environment with a number of useful utilities built-in.
OK, Genius, so you always retrieve the data? No, there are limits to to what this recovery method can do. In the case of physical damage, recovery methods based on software are hit or miss at best. I had the case of a computer that came out of restaurant fire which resembled a molten plastic slag rather than a computer. The recovery experts at Drivesavers (www.drivesavers.com) were able to disassemble the drive and recover all the critical data.
There is also the case of "Whoops! I forgot to do that." I was upgrading a client's Mac G4. This also involved upgrading Microsoft Office 2004 to version 2008. Everything went well. The new version was installed without incident and the prior version was removed. However, when the client wanted to check her calendar in Entourage, I knew that I blew it. I forgot to backup the Entourage data because I was concentrating on Word, Excel, etc. My next thought was - "What do I tell the client ?" Various scenarios were contemplated; i.e., the calendar never existed, Entourage self-destructed, unknown government agents confiscated the data under order of a secret federal court. After a brief discussion with the client, we determined that the calendar data was gone and we dealt with it.
So, the bottom line is backup your data. After you back it up, well, back it up again. Then make sure that the backup works and back it up a 3rd time. Murphy's Law of Computing says "For every action, there is an equal and opposite malfunction" and "He who laughs last probably made a back-up."