How To Recover Windows Product Key (Serial Number) From Registry, Even If PC is Unbootable

Your installation of Windows no longer boots, and unfortunately you don't have a copy of your Windows product key in order to reinstall the operating system? Don't worry, it's possible to recover Windows Product Key from registry in offline mode, even if Windows is no longer bootable.

This article explains how to find and recover Windows Product Key from the registry, extract Windows Serial Number from registry in offline mode, and get Windows CD Key from unbootable computer.

Contents

1. Intended audience of this article
2. Solution in a nutshell
3. Extracting DigitalProductId from registry
4. Decoding DigitalProductId
5. References

1. Intended audience of this article

This article is for people who want to reinstall Windows, but lost or forgotten Windows Product Key.

Using Registry of your old Windows installation, you can retrieve Product Key once upon a time used to install Windows. This method works even if Windows is broken and unbootable, or if your computer crashes during startup.

All you need to recover your Windows Product Key is readable (non-broken) HKEY_LOCAL_MACHINE\SOFTWARE Registry hive.

2. Solution in a nutshell

Boot into Emergency Boot Kit
Run Emergency Boot Kit Registry Editor, choose Windows installation and open HKEY_LOCAL_MACHINE\SOFTWARE Registry hive
Export HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion registry key to text file on USB thumbdrive.
Boot into Windows, open registry key dump in Notepad, copy DigitalProductId value into the clipboard.
Paste clipboard into Javascript form on this website to decode your Product Key.

3. Extracting DigitalProductId from registry

1) Download Emergency Boot Kit and deploy it USB thumbdrive according to the instructions, then set up your BIOS to boot from USB thumbdrive. Demo version of Emergency Boot Kit will suffice for the purpose of this article.

2) Boot Emergency Boot Kit and run Registry Editor from the main menu:

Recover Windows Product Key With Emergency Boot Kit - Main Menu

3) Wait for Emergency Boot Kit Registry Editor to start:

Recover Windows Product Key With Emergency Boot Kit - Waiting for Registry Editor to Start

4) Choose Windows Installation to extract Product Key (this screen will not appear if you have one copy of Windows installed on your PC):

Recover Windows Product Key With Emergency Boot Kit - Choose Windows Installation to Extract Product Key

5) Choose HKEY_LOCAL_MACHINE\SOFTWARE on this screen:

Recover Windows Product Key With Emergency Boot Kit - Choosing Registry Hive containing Windows Product Key

6) Emergency Boot Kit Registry Editor is loading Registry Hive with Windows Product Key:

Recover Windows Product Key With Emergency Boot Kit - Registry Editor is Loading Registry Hive

7) Using arrow UP and DOWN keys on keyboard, go to Microsoft key and press ENTER:

$Recover Windows Product Key With Emergency Boot Kit - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft key$

8) Using arrow UP and DOWN keys on keyboard (and optionally PAGE UP and PAGE DOWN), go to Windows NT subkey and press ENTER:

$Recover Windows Product Key With Emergency Boot Kit - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT subkey$

9) Using arrow UP and DOWN keys on keyboard, go to CurrentVersion subkey and press ENTER:

$Recover Windows Product Key With Emergency Boot Kit - HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion subkey$

10) Press TAB to switch input focus to the right panel. Scroll down with arrow keys and PAGE DOWN / PAGE UP keys:

Recover Windows Product Key With Emergency Boot Kit - Switching to Value Edit Mode in Registry Editor

11) Make sure DigitalProductId value of type REG_BINARY exists:

Recover Windows Product Key With Emergency Boot Kit - Looking For DigitalProductId Value

12) Press F3 on the keyboard to open Registry Key Export dialog window, then click [...] button with a mouse:

Recover Windows Product Key With Emergency Boot Kit - Registry Key Export Dialog

13) In this Save File common dialog, click on the USB thumbdrive with Emergency Boot Kit, then click on the text area next to "File Name:" label and type some file name from keyboard. File name must have .txt suffix.

Recover Windows Product Key With Emergency Boot Kit - Saving Dump of Registry Key

14) Click OK to confirm export of Registry Key to the file:

Recover Windows Product Key With Emergency Boot Kit - Confirm Export of Registry Key

15) Message like this should appear on the screen:

Recover Windows Product Key With Emergency Boot Kit - Registry Key Has Been Exported Successfully

16) Choose "Reboot" in the main menu of Emergency Boot Kit:

Recover Windows Product Key With Emergency Boot Kit - Reboot

Unplug Emergency Boot Kit from USB port and boot into Windows (maybe on the different PC, where you are browsing this page). Plug USB thumbdrive with registry key dump and open My Computer: