To gain access you need to do TWO things:
1) Take ownership. Taking ownership doesn't give you access to the files and folders, but it DOES allow you to then go ahead and change their access control lists. Make sure you do this for the folder as well as all files and subfolders.
2) Change the access control list. You typically want to grant "Full Control" access to your account. Again, be sure to do this for the folder as well as all files and subfolders.