When there are problems related to the registry and failure to boot one of the best options is to save files and install a fresh copy of Windows.
Drivers and applications need to be reinstalled.
Windows can save the files to Windows.old.
Then important files can be restored from Windows.old.
This is a custom install.
Alternatively you can manually back up files using notepad or another operating system.
This is a clean install.
Find a flash drive that you can format ( > or = 8 GB)
On a working computer create a bootable flash drive with the Media Creation Tool (MCT) (Windows 10 iso):
https://www.tenforums.com/tutorials/2376-create-bootable-usb-flash-drive-install-windows-10-a.html https://www.tenforums.com/tutorials/9230-download-windows-10-iso-file.html
https://www.microsoft.com/en-us/software-download/windows10
On the problematic computer insert the bootable MCT.
Power on the computer and boot to the flash drive.
(turn off secure boot, fast boot, ultra fast boot, etc. as needed)
Follow these links for a custom install (saves files to windows.old and installs a fresh version of Windows).
Drivers and Applications are reinstalled.
Important files are then restored from Windows.old
https://www.tenforums.com/tutorials/120352-custom-install-windows-10-a.html
https://www.tenforums.com/tutorials/148005-how-restore-files-windows-old-folder-windows-10-a.html
If you prefer clean install then manually backup files.
All partitions are deleted making an unallocated disk drive.
The Windows iso then creates the default partitions.
Drivers and applications are reinstalled.
Files are manually restored.
https://www.tenforums.com/tutorials/1950-clean-install-windows-10-a.html