On Windows 7 pro, I changed a drive's (M:) permission using it's properties with a account which have administrator's (not Standard User) right for all "USERS" but it affected on my admin account too and I get "Access Denied" when I try to access the drive.
Now, I'm unable to change it again with the same admin account and I get "You don't have permission to view or edit this object's permission settings" error on Security tab of the drive's properties. I also tried built-in "Administrator" account but I couldn't access again.
How can I change this drives permission again? is there any higher level user than "Administrators" I could use it?