Hello,
Generally, we can refer to the following path to find out the BitLocker recovery key, because this is a personal information, so please kindly try to find carefully if the key was saved in below places:
Finding your BitLocker recovery key in Windows - Microsoft Support
If you are unable to locate the BitLocker recovery key and can't revert any configuration change that might have caused it to be required, you’ll need to reset your device using one of the Windows recovery options. Resetting your device will remove all of your files.
Microsoft support is unable to provide, or recreate, a lost BitLocker recovery key.