Windows 10 is no longer making regular backups of your registry and have not been doing so for a while.
In a recently published support article, Microsoft confirmed that since the April 2018 Update for Windows 10 they had been making empty 0-byte backups of your registry hive with the intent of reducing the amount of space your Windows 10 installation consumes.
Starting in Windows 10, version 1803, Windows no longer automatically backs up the system registry to the RegBack folder. If you browse to to the \Windows\System32\config\RegBack folder in Windows Explorer, you will still see each registry hive, but each file is 0kb in size.
This change is by design, and is intended to help reduce the overall disk footprint size of Windows. To recover a system with a corrupt registry hive, Microsoft recommends that you use a system restore point.
If you prefer however to have this valuable feature still available you can re-enable it, ironically via a registry edit.
If you have to use the legacy backup behavior, you can re-enable it by configuring the following registry entry, and then restarting the computer:HKLM\System\CurrentControlSet\Control\Session Manager\Configuration Manager\EnablePeriodicBackup
Windows backs up the registry to the RegBack folder when the computer restarts, and creates a RegIdleBackup task to manage subsequent backups
A backup is, of course, useless without a method of restoring it. This is somewhat complicated however and is detailed in an article by PureTechInfo here.