Fix registry errors for free by using the free edition of CCleaner or by using the Registry Editor included in Windows. While CCleaner scans for and fixes registry errors automatically, the Registry Editor requires user input.
To download CCleaner, click Download Free Version, and then select Free Download. Although the free edition lacks features such as real-time monitoring, scheduled cleaning and premium support, it can help fix the registry. Install the program, and launch it.
Navigate to the Registry tab on CCleaner, select the categories you want the application to scan, and click Scan For Issues. Once the scan is complete, select the items you want to fix, and click Fix Selected Items.
Your operating system or an application you use may indicate the key that is causing issues. When you know what registry key you need to fix, you can fix it manually. Click the Start button, type "regedit.exe" and hit Enter. With the Registry Editor open, use the folder view on the left to navigate to the directory that holds the faulty key, and change its value according to your needs. As some keys may be case sensitive, it is a good idea to be careful when renaming keys.
Before using either method, create a backup of your registry in case the repair attempt causes more damage. To do so, click File on the menu bar, select Export, indicate a directory and click Save. You can then use the Import feature under the File menu to restore the registry.