20 Oct 2026 · 5 min read
BitLocker recovery key: where to find it, and what to do if you can't
A blue screen asking for a 48-digit key you have never seen. Here is where Windows keeps that key, how to match the right one, and your honest options if it is gone.
It usually happens out of nowhere: the computer starts up to a blue screen headed BitLocker recovery and asks for a 48-digit key. Most people who ring us about it never knew their drive was encrypted. Many newer Windows computers turn on BitLocker (or "device encryption") automatically when they are set up with a Microsoft account, and quietly save the key to that account.
1. Write down the Key ID
The recovery screen shows a Key ID, a short code of letters and numbers. A computer can have several keys over its life, and the Key ID tells you which one this screen wants. Write down the first eight characters.
2. Look in the Microsoft account that set the computer up
On your phone or another computer, go to aka.ms/myrecoverykey and sign in with the Microsoft account used on that computer. You will see a list of keys, each with its Key ID. Find the one that matches your screen and type that key in.
- Not there? Try any other Microsoft account you have used, including old Hotmail or Outlook addresses.
- If a family member or a shop set the computer up, the key may be in their account.
- A work or school computer: your organisation usually holds the key. Ask their IT team, or try aka.ms/aadrecoverykey with your work account.
3. Check for a saved or printed copy
When BitLocker is turned on by hand, Windows asks where to keep the key. Look for a printed page, or a text file named BitLocker Recovery Key followed by the Key ID, on a USB stick or another computer.
Why it suddenly asked
BitLocker asks for the key when something about the way the computer starts has changed and it can't be sure it is still the same, untouched machine. Common triggers:
- A BIOS or firmware update, or the BIOS being reset
- A change to Secure Boot settings (see Secure Boot violation)
- A repair, such as a new drive or a motherboard repair
- Some Windows updates, and occasionally a USB device or dock left plugged in at start-up
It is a security feature doing its job, not a sign that you have been hacked.
If the key can't be found
This is the hard part, and it is better to hear it plainly: without the key, nobody can unlock the drive. Not us, not Microsoft, not a data recovery lab. Anyone offering to "bypass" BitLocker for a fee is not being honest with you.
What can be done is to wipe the drive and reinstall Windows so the computer works again. Before that, check what you can get back from elsewhere:
- Files that were syncing to OneDrive are safe in the cloud. Sign in at onedrive.com to see them.
- Photos backed up from your phone to iCloud or Google Photos are still there.
- Anything copied to an external drive or USB stick.
Once you're back in: make sure it can't happen again
- Go to aka.ms/myrecoverykey and check the key for this computer is listed
- Keep a copy somewhere other than the computer itself: printed, or in a password manager
- Set up a backup, so a lost key would cost you an afternoon rather than your photos
If you'd like help
We help owners work out which account the key is in and, if it really is gone, reinstall Windows and put back whatever can be recovered from backups. It falls in our Software & setup range of $80–$180, with a fixed price agreed first. See Windows 11, reinstalls and BitLocker help. We only help the owner of the computer.