Lost Bitlocker recovery key on your Dell
No, I have no way of getting a truly lost key and/or decrypting your system, but if you unexpectedly get the Bitlocker recovery key screen (especially after a power loss/strange messages of lost settings/BIOS update), you might not actually have a real problem.
When losing BIOS settings, for example after a total power loss with a weak CMOS battery, many (all?) Dell systems set their TPM chip to "deactivated", and this error message might be the result. Check your BIOS settings -- TPM should be set to "Enabled" (Security/TPM security, you might have to first "activate", click "Apply", and then "enable" TPM).
This might also happen after a BIOS update.
Do NOT reset anything inside the TPM settings, or you will lose access to your data for sure!