Hi there,
This error message can occur for a couple of different reasons , major reason the registry gets disabled is due to malicious viruses. By disabling access to the registry, the virus can prevent the user from repairing their system. I would suggest you to run a deep malware scan.
-Navigate to User Configuration – Administrative Templates – System.
-In the right hand pane, double click on Prevent access to registry editing tools.
-If the setting is set to Enabled, you can change it to Not Configured or Disabled. Now try to run the registry editor and see if it works
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