Fix damaged files

The only way to discover if a file is still usable is to recover it to a different drive, then attempt to open it. If the application reports the file as corrupt, or it displays garbage then your attempts have been unsuccessful. However, all may not be lost, as it might be possible to retrieve part of the file.
   You'll have most luck with text files, because even if parts of the file have been overwritten you should still be able to get some of the text back. Program files are more troublesome however, because if any part of them is corrupt then the file is lost. When it comes to application documents like Word or Excel files, Zip archives or image files, it might be possible to retrieve part of the data contained in that file, but it won't come cheap.
   Software recovery specialists are falling over themselves to offer tools that are designed specifically to rescue data from damaged files, and thankfully most offer trial versions of their products to give you an idea of what can be retrieved. You're then left to make the decision as to whether or not the asking price is worth it to rescue an individual file or group of files.
   It's worth noting that the options below can also be used to try and recover data from files that have become corrupt through everyday use in Windows. In fact, your chances of successful data retrieval are far higher with a file like this as opposed to the fragments of a file you recovered using the data-recovery techniques covered elsewhere on this site.

Recovery solutions
One of the biggest providers of file recovery is Officerecovery.com, which has products to cover a wide range of file types, including Microsoft Office, Zip archives, various image files and much more besides. A full list of products is found here. Prices range from US$99 all the way up to $899 for a product that rescues data from multiple file formats.
   If you're looking to recover a Word, Excel or Access file, you'll find a cheaper solution at Cimaware Software (see here). Prices are in pounds sterling, and start from £59 for the Word recovery utility. They're easy to use too: just install the program, let it check for an update, then it'll start the recovery wizard. Just drag your file on to the window (or click the Browse button to find it through a conventional Open dialog box) and click Recover.
   Once complete, the program will tell you what it managed to salvage - click the View button to see a preview of what it's found. If you're happy with the results, you'll need to purchase the full version before it'll let you save the recovered file to your hard drive.
   Ontrack offers free Zip repair functionality in the demo version of its all-purpose recovery tool, EasyRecovery (see here). This might help you rescue part of an archive and is well worth adding to your data recovery arsenal. Once installed, click File Repair followed by Zip Repair to access it. You'll also see cut-down versions of the Word, Excel, Access and PowerPoint repair tools that you can try too.
   If you only want to rescue an individual Office file, however, you'll find a still-more affordable answer online at Doctor Recovery (see here). The walkthrough below shows you how it works. The site supports Word, Excel, Access and PowerPoint files, and the cost per file is $9.99-$39.99 depending on its size.