As we can see I deleted the entry of 'Authenticated Users' and 'Users' from the security tab in C: local properties. I can still use every installed program on the PC, but unable to access C:, the message is: Denied Acess, any way to revert it?

  • 5
    You have destroyed too many permissions on essential Windows folders. You need to reinstall Windows from scratch, and avoid doing this again.
    – harrymc
    Jan 4, 2021 at 19:36
  • 1
    harrymc has the right of it - there's no automated permission repair on Windows. It is technically possible to recreate the permissions yourself, but it would be a very poor use of your time. Just reinstall.
    – Karu
    Jan 5, 2021 at 2:24
  • @Karu I have so many dependencies in this system. I prefer to recontrol C:
    – JamesB
    Jan 5, 2021 at 11:07
  • What you want to do and what you can do are not the same thing. This is a good lesson: don't mess with permissions on C drive unless you really know what you're doing. Jan 7, 2021 at 2:10

1 Answer 1


You cannot repair the damage you've done to permissions on the C drive without a reinstall of Windows. There are too many little details that cannot be known. There are the OS default permissions which are already complex and irreproducable, and then there are the permissions set by individual applications, and finally there are likely other changes you made to permissions besides simply removing the two groups you state you removed.

The correct course of action at this point is to perform a reinstall of Windows.

  • 1
    ... and then set up proper automated backups that would be able to completely rollback the system after such mistake. Veeam Agent is my usual recommendation, I've been using it with great success. It does complete system snapshots in background and can restore a completely destroyed OS.
    – gronostaj
    Jan 11, 2021 at 8:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.