how to find my previous msn account linked to my PC ?

90054882 45 Reputation points
2026-05-09T17:20:41.0033333+00:00

Hi

I have dell Inspiron with win 10, Last year I upgraded to win 11 and added 1 TB SSD,

everything was perfect till I wanted to make a fresh win 11 installation.

I discovered that my 2 SSD D&E partitions were BitLocker encrypted!

I only added my msn account.

I searched for them, but I only found keys for C which already decrypted!

windows only gave me the ID

for example, for D partition

Numerical Password:

  ID: {B452B948-6AD2-4A94-9687-AE0970267859}

  Backup type:

    Microsoft account backup

External Key:

  ID: {215256DD-6EC8-4A61-8165-DBB3CC263AA1}

  External Key File Name:

    215256DD-6EC8-4A61-8165-DBB3CC263AA1.BEK 
```I searched in windows for that BEK file everywhere in PC and flashes and I only found in my USB flash an empty file called recovery!

tried to search in all USB flashes but hopeless.

my question is where to find BitLocker keys the time I didn't find them in my only yahoo account in win 10?

Thank you
Windows for home | Windows 11 | Accounts, profiles, and login
Answer accepted by question author
Thomas4-N 23,585 Reputation points Microsoft External Staff Moderator
2026-05-13T08:56:38.7266667+00:00

Hello 90054882,

Unfortunately, Microsoft can't resend or copy a BitLocker recovery key from one Microsoft account to another. The key is uploaded once to whichever account was signed in when encryption turned on, and that's the only place it lives.

A couple of things still worth trying before you write off D: and E::

Don't assume it was the Yahoo account. The "Microsoft account backup" label only tells you it went to some Microsoft account, not which one. Sign in at https://account.microsoft.com/devices/recoverykey with every email you've ever used on that PC — a Gmail, an old Hotmail/Live alias, a work or school address. People often have a Microsoft account tied to an address they don't think of as one.

If it really was the old Yahoo-linked account, the dead Yahoo inbox doesn't automatically kill the Microsoft account — they're separate. But after ~10 years inactive it's almost certainly been closed, and closed accounts can't be reclaimed. Still worth trying the account recovery form at https://account.live.com/acsr ; it doesn't require access to the Yahoo mailbox.

If none of that turns anything up, and no other USB has the .BEK, there's unfortunately no supported way back into D: and E: — formatting is the only option left.

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  2. AI answer

    2026-05-09T17:20:55.31+00:00

    The previous Microsoft account username cannot be derived from the BitLocker key IDs, Dell service tag, or Windows product key. To locate a previous Microsoft account that may have been used on the same PC, only the following supported methods are available:

    1. Check products and services where the account was used
      • Review all personal email accounts (Outlook, Gmail, etc.) for messages from Microsoft about:
        • BitLocker recovery keys
        • Windows, Microsoft 365, Xbox, or Store purchases
        • Subscription or security notifications
      • Any such email will show the Microsoft account address it was sent to.
    2. Look on devices or apps where the old account might still be signed in If there is any other device where the old account might still be active:
      • On Windows 10/11:
        • Select Start > Settings > Accounts.
        • Under Email & app accounts, check the email addresses listed; these are Microsoft account usernames associated with that device.
      • In Office apps (Word, Excel, etc.):
        • Open an Office app.
        • Go to File > Account.
        • Under Product Information, check Belongs to for the Microsoft account.
      • On Xbox (if ever used):
    3. Use the official “forgotten username” flow (only if security info was set up)
      • If security info (alternate email or phone) was added to the old account, follow the steps in “forgotten your Microsoft account username” from the Microsoft account help pages. This uses existing security info to show the account name.
    4. If no security info and no traces in products/services
      • If the username cannot be found via email receipts, signed-in devices, or the official username-recovery flow, it may indicate that the Microsoft account has been closed. In that case, only the documented reopen your Microsoft account process applies.

    There is no supported way for Microsoft Support to disclose or look up a previous Microsoft account solely from a Dell service tag, BitLocker ID, or Windows product key, and they must follow strict validation policies before providing any account information.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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