Regedit is a file belonging to the Microsoft Windows Registry Editor. This executable resides in the Windows directory on your computer. If this file is corrupt, you will be unable to access the editor. Thankfully, you can replace this executable using the Microsoft System File Checker utility. This command-line tool can scan and replace specific system files such as Regedit.exe. Prior to running this utility, you should first rename the original Regedit file. This ensures that the application successfully reinstalls a new copy of Regedit in your Windows directory.
Click "Start," then type "C:\Windows" in the "Search programs and files" field and press "Enter." This opens the Windows folder in a new window.
Locate and right-click the "Regedit" executable. Click "Rename," then change to "Regedit.bk." This does two things. First, it keeps the file on your system for backup purposes. Secondly, and most importantly, the directory no longer has a "Regedit" executable. This means that even if the System File Checker fails to acknowledge a problem with Regedit, it will still be replaced.
Minimise the Windows folder. Click "Start," and type "Prompt." Right-click "Command Prompt" on the list of results, and click "Run as administrator."
Type "SFC /Scanfile=C:\Windows\Regedit.exe," and press "Enter." This executes the System File Checker utility. This application will determine that the "Regedit.exe" file is no longer in the Windows directory, and will simply reinstall a new one.
Type "Exit," and press "Enter" once you see the message including "Resource Protection found corrupt files and repaired them." This closes the prompt. Maximise the Windows folder. Double-click the new "Regedit" file. The Registry Editor should now load.