If your sister has the key ID, Microsoft may be able to help recover the BitLocker key, provided that the device was backed up to Microsoft Entra ID or Active Directory. If the device is Microsoft Entra joined or hybrid joined, the recovery information can be retrieved from Microsoft Entra ID. If it is domain joined, recovery information can be retrieved from Active Directory.
To assist her, the helpdesk or IT support should verify her identity and use the key ID to locate the recovery password. It's important to note that if the recovery key was not saved or backed up, it may not be possible to recover the data on the device.
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