How to reset NTFS permissions on System drive on Windows 7 or Windows 2008 R2 ?

After Win 2008 R2 was installed, some files on drive C: were not accessible anymore and I was getting “Access Denied”

I tried to right-click/properties on the folders that were not accessible and changed their owner and changed permissions but still some folders were still inaccessible not matter what I did. After some research, it turned out the tool “cacls” that allows one to display or change ACLs (access control lists) can help to reset ACLs.

In Windows 7 or 2008 R2 it is called “icalcs”. To reset files permissions:

1. Run “cmd” as Administrator

2. Go to the drive or folder in question, for example:

cd /d c:

cd /d d:

3. To reset all the files permissions, type:

icacls * /t /q /c /reset

The Microsoft TechNet site has documentation for the icacls command

4. And that’s it!

After that, the files permissions were reset and I could access them back again.

Update:

It is possible that “icacls” might fail. For that try to take ownership of the files first.

Just before Step (3), please type the following command:

takeown /r /f *