Introduction In this data recovery step-by-step guide, technologies that Windows administrators can use to retrieve lost or corrupted data. Data recovery topics include how to create boot disks, calculate disk cluster size, and recover corrupt boot sectors. How to recover data As a card-carrying computer geek, we often get emails from customers who have lost computer data. The common reasons are the data has been accidentally erased or damaged by a virus or the hard drive itself is the problem. Whatever the cause, the one constant is this: People who are not IT professionals ever back up their data. Although the data recovery process itself can be complicated, the idea behind the process is simple. Data recovery is possible because a file and information about a file are two different things, stored in two different places. The Windows operating system uses a file allocation table (FAT) to keep track of which files are on the hard drive and where those files are stored. The best way to describe how a hard drive's file system works is to compare it to a book. The FAT is like a table of contents, while the actual files on the hard drive are like the pages in the book. To illustrate how the data recovery process works, let's take this analogy one step further. You need to install a new kitchen sink, so you buy a book on home improvement. The table of contents tells you that the chapter on installing a kitchen sinks starts on p. 40. If you rip the table of contents out of the book and shred those pages, have you lost the information on installing the sink? Of course，not. The chapter on installing a sink is still in the book. It's just going to be harder to find. Data recovery works the same way. When data needs to be recovered, it often only the FAT is messed up. The actual file that needs to be recovered may still exist on your hard drive in perfect condition. If the file still exists, is undamaged, and is not encrypted, it can be recovered. All you have to do is to find it. On the other hand, if the file itself is damaged or missing or encrypted, recovery through normal means is impossible. That doesn't mean recovery is impossible, only recovery through the usual means. You can't magically recover what isn't there.