If you have the key saved as a text file, you must manually open the file on a separate computer to see the recovery key.
Alternatively, reinstall Windows using an installation disc.
First, your PC will download the Windows installer (if there is not one built into Windows RE). Then, your PC will run the Windows installer. The installer will erase your drive and install Windows onto your PC. Finally, you will be prompted to complete initial setup, which should not be so hard, especially because Cortana guides you through setup on the Windows 10 Fall Creators Update (version 1709) and later.
