Hi, good day!
If you don't need any of the files on the laptop, we can focus on getting Windows reinstalled rather than recovering the BitLocker key.
Since Reset this PC is failing with “No changes were made,” the next step would be a clean installation of Windows using a bootable USB installer. This will erase the existing Windows installation, including the BitLocker-encrypted data, and give you a fresh Windows installation.
Find another working computer then download the Media Creation tool (Click Download tool now). Use the tool to "Create installation media (USB flash drive at least 8GB in size) to install Windows". Instructions inside the link.
Note: Please make sure to uncheck the "Use the recommended options for this PC" box. Please check the link below for more details.
Insert the USB Installation media into your computer. Please change the boot order in the Bios Settings. Boot your PC from the Installation Media you created.
Kindly refer to the link below on How to Perform a Clean Install for more details.
I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below.