Hello,
There's not much us (as in the Microsoft Learn Community) and Microsoft themselves can do to help you find the account that you set up BitLocker with. Try any work or school accounts that you may have signed into, and any other alternative Microsoft accounts you may have and try to find the key there.
For personal accounts, go to https://aka.ms/recoverkey and try to find your key there. If you're trying with a work or school account, look on https://aka.ms/aadrecoverykey.
If you are still unable to find the recovery key, unfortunately, you will have to clean install Windows, which will cause you to lose all data on the device.
I hope this information helps.