I agree with the above posts. as well as....
I have just run into this problem yesterday.
You may need to take ownership of the file or folder
Right Click the File or Folder
Click Security Tab
Click Owner Tab
You may have to click Edit to continue taking ownership
You should see 2 entries (maybe more)
Find your name and select it
If this is a folder, Check "Replace owner on subcontainers and objects
That is a rough draft off the top of my head, there may be other steps, but if you get that far, you should be able to figure out the rest.
See if that works.
The alternative is the TakeOwn Tutorial
You should not take ownership of files and folders at will.
only when it is needed, and ONLY on files/folders you have created or downloaded
Not on windows system files and folders, or the entire C: drive as has been posted around.