If a file physically damaged, your only hope of recovering it (without a backup) is to reconstruct the file. Many applications, such as Microsoft Office, place uniform headers at the beginning of files to designate that the file belongs to that application. Some utilities can be used to manually reconstruct file headers so that at least a portion of the file can be recovered. In many cases, data loss is related to the FAT rather than to the data itself. For instance, when you delete a file, it's usually moved to the recycle bin. But if you delete a file from the recycle bin or remove it in such a way that causes it to never be placed in the recycle bin, the actual file is not deleted. Instead, the operating system changes the first letter of the file name in the FAT to a sigma sign. (Older file systems used a question mark.) The operating system also writes zeros to cluster chain entries within the file allocation table as a way of showing that the disk space previously used by the file is still available. When a file is erased in this manner, the file itself still exists until another file overwrites the area of the hard disk that was previously used to store the file that has been erased. A similar concept also applies to formatting a hard disk as well as corruption of the FAT. In these cases, the files still exist. They've simply been removed from the FAT (or renamed to something that Windows is designed to not display). This is the basic concept of data recovery techniques. And it is the element which we used for designing EASEUS Data Recovery Wizard.