Hello @Ujjal Nath
You can follow the next articles:
Find recovery key: https://support.microsoft.com/en-us/windows/finding-your-bitlocker-recovery-key-in-windows-6b71ad27-0b89-ea08-f143-056f5ab347d6
Bitlocker recovery guide: https://learn.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-recovery-guide-plan
Hope this helps with your query,
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