If the registry settings for an application become corrupt, there are several methods you can use to try and repair them. Here are some of these methods, in order of escalation. I'm assuming that the application was well-designed and comes with a Windows Installer package for installing the application on your system.
1. Open the application, select Help from the menu, and click Detect and Repair.
2. Open Control Panel, open Add Or Remove Programs, select the application, click Change, and follow the instructions presented to repair the application.
3. Click Start, then Run, type msiexec /fu package or msiexec /fm package to repair either the per-user or per-computer settings as desired. Here package is the .msi file used to install the application. This method is great for administrators since you can repair apps remotely using this approach.
4. Open regedit.exe and navigate to HKCU\Software\Company\Program\Version\
and delete either the per-user or per-computer settings for the application (but back up the registry first!) and then restart the application. This is the method of next to last resort.
5. Copy the registry keys for your application from another computer with similar configuration to your machine and on which the same version of the same application is installed. This is definitely the method of last resort, but it can work—sometimes!
Mitch Tulloch is President of MTIT Enterprises, an IT content development company based in Winnipeg, Canada. Prior to starting his own company in 1998, Mitch worked as a Microsoft Certified Trainer (MCT) for Productivity Point International. Mitch is a widely recognized expert on Windows administration, networking and security and has written 14 books and over a hundred articles on various topics. He has been repeatedly awarded Most Valuable Professional (MVP) status by Microsoft for his outstanding contributions in supporting users who deploy Microsoft platforms, products and solutions. Mitch is also a professor at Jones International University (JIU) where he teaches graduate-level courses in Information Security Management (ISM) for their Masters of Business Administration (MBA) program. For more information see http://www.mtit.com.