If you are using Microsoft Windows, your operating system stores all of its settings in a large database called the registry. Even if you don’t know what the registry is, the programs you use every day change it. Editing the registry can help you fix serious problems with your operating system by learning how to use the regedit command, a Windows program designed to modify the registry.
Steps

Step 1. Back up the registry before making any changes to it
Making the wrong registry changes can cause your Windows system to stop working. Backing it up ahead of time is a good idea. The easiest way to do this is with System Restore, a utility built into Windows to create a system restore point.

Step 2. Start the Regedit program
Click on the "Start" button and then click on the "Run" command. In the dialog box that appears, enter "regedit" in the text box and then click the "OK" button.

Step 3. Get familiar with the Regedit interface
When the program starts, you will see a window divided into 2 panels. The right pane will be empty and the left pane will show a list of 5 folders, all starting with the letters "HKEY". These are the 5 "branches" or main registry keys. Clicking on the plus sign next to each folder will allow you to navigate deeper into each key.

Step 4. Navigate to the key you want to make changes to
If you are not sure which key you need, it is best to use the Regedit help file or the online support site to determine what exactly you want to do. The Windows registry is huge and contains important system files that can cause serious problems if changes are made.

Step 5. Make the necessary changes to the key you are interested in
Once you've navigated to the key you want in the left pane, right-click on it. A context menu will appear with several options.
- Click on "New" to add a new key below the key you have chosen.
- Click on the "Delete" button to delete the key. If the selected key is associated with a program that you uninstalled, you can safely delete the key.
- Click on the "Export" button to save all the information contained in the selected key on your hard drive. This is a good way to back up an individual key before making any changes to it.

Step 6. Add new registry files that you want to import into the registry
Registry keys are saved with a.reg extension, which is actually just a regular text file. This is useful if you are trying to add information to the registry from an internet source that is in plain text. Copy the text into a text editor (eg Notepad), and save the file with the.reg extension. Once you have saved the file, simply double click on it to add it to the registry.

Step 7. Consider using System Restore as an alternative
If you are using the regedit command to try and fix a major problem with your operating system, remember that System Restore automatically creates restore points on a regular basis. You can easily choose to restore your system's configuration to the date before the problem occurred, and this will restore the registry in the process.