If your PC will not boot and you need the product key to reinstall or reactivate the system, there are practical ways to recover it from the offline drive. Here are safe procedures and alternatives: connect the drive to another PC, export the registry hive and use tools to read the key. The process differs for digital licences or those linked to a Microsoft account. If you purchased your licence from Licensgo, keep your documentation and contact support if you need help.

1Before you start — what to check

Check whether you have a traditional product key or a digital licence linked to your Microsoft account. Digital licences do not always expose a readable key on the drive: activation then takes place through your account. If you are unsure, keep the drive and proceed carefully.

If you plan to reinstall Windows, keep your current licence details to hand. For a clean reinstall, you can consult the guide to activating Microsoft Office 2024 Professional Plus for similar Microsoft product activation procedures.

  • check whether the licence is linked to your Microsoft account;
  • avoid writing to the original drive;
  • prepare another PC with reading tools or a USB drive adapter.
Quick tip

If you recently purchased the licence and registered it with your Microsoft account, try signing in on the Microsoft website before attempting to recover the key.

2Step 1 — mount the offline disk on another PC

Shut down the faulty PC and remove its HDD or SSD. Connect it to another computer using a SATA cable or USB-to-SATA adapter. Use a read-only connection if possible (some adapters and enclosures support this) to avoid accidental changes.

Open the mounted drive's file system and navigate to Windows\System32\config. This contains the registry hives, particularly the SOFTWARE file with information about installed keys.

  • use a USB-to-SATA adapter for convenience;
  • avoid booting from the mounted drive;
  • work in read-only mode whenever possible.
Hardware tip

If you do not want to remove the drive yourself, consult a technician or use an external enclosure to avoid invasive work.

3Step 2 — export and read the SOFTWARE hive

Copy the SOFTWARE file, without opening it directly, to a folder on the host PC. You can load the hive with a command such as ‘reg load HKLM\TempHive C:\path\to\SOFTWARE’ in PowerShell on the Windows host, then export the required keys.

Useful tools: ProduKey (NirSoft) can read product keys from exported hives; some PowerShell scripts can extract the ‘ProductId’ value or OEM key. Only use trusted software downloaded from the developer's official website.

  • export the SOFTWARE hive instead of opening it on the original drive;
  • use ProduKey or trusted PowerShell scripts to read the key;
  • unload the mounted hive with ‘reg unload’ when finished.

4When the licence is digital / linked to a Microsoft account

Digital licences (digital entitlement) do not always expose an extractable product key: activation relies on the link between hardware and account. In this case, you will not find a readable key in the registry. To reactivate, sign in with the same Microsoft account after installation and use the activation troubleshooter.

For instructions on reactivating a Microsoft product after reinstalling, see our Windows 10 Pro activation guide, which includes practical steps and advice for common problems.

  • if you have a digital licence, try signing in with your Microsoft account;
  • use the Windows activation troubleshooter;
  • if necessary, contact Microsoft support for complex transfers.

5Precautions and when to replace the licence

Do not work directly on the original drive: create an image or copy first. If the drive has physical faults, consult a data recovery specialist rather than forcing operations that could make matters worse. If the key is corrupted or the OEM licence cannot be transferred, buying a new licence may be worthwhile.

For a replacement, consider a Microsoft Windows 11 Professional licence or Microsoft Windows 10 Professional licence. If you need an Office key, also consider a Microsoft Office 2024 Professional Plus licence. If you have any questions, Licensgo support can also help by email or through our contact form.

  • always back up or create an image before starting;
  • if the drive is physically damaged, avoid DIY recovery attempts;
  • consider buying a new licence if the key cannot be recovered.
When to call support

Contact Licensgo support if you bought your licence from us and cannot find the key: we can check your order and suggest the best solution.