A corrupt file is one that has become unusable. Viruses, malware and programs closing prematurely can all corrupt a file. While the file is corrupt, you won't be able to use it. You can fix this problem and uncorrupt the file by using some free tools available online. Many of these programs offer a free demo that you only need to purchase if you want to continue using it after the trial period.
Download and install Registry Mechanic. This gives you six free sessions for recovering corrupt files in your Registry, such as hardware drivers that make physical pieces of your computer function. The program costs $29.95 as of 2011 after the six-session trial.
Download and install 1 Click PC Fix. This program will fix corrupt files throughout your system by clicking the "Start Scan" button. The software trial fixes the first 50 errors; after that you'll need to register to continue use.
Navigate to the Disk Recovery Software site. Download and install a program for fixing the particular kind of file you want to uncorrupt. Install "Word Recovery File" for Microsoft Word files and "ZIP File Recovery" for ZIP archives. The programs are free on a trial basis.