copy protected folders from old, to new hard disk

I am attempting to reformat my computer, but before I do so I want to copy all my data to another computer so that I can later copy it back to the original computer. I have bought an USB hard drive enclosure kit so that I can use the USB connection to connect the 2.5" hard disk to my Desktop computer.
The problem I am having is that I can see the folder I want to copy but when I try to open it, it is says that the folder is inaccessible.
There were two accounts, the primary account was password protected while the Guest Account was not. When I plug the hard disk into the second computer I can view the guest account folders but not the primary account folders. I suspect it is because it was protected. Also when I check the properties in that folder it shows it as being empty, but it should defiantly contain files.
Any advice on how I can unlock this would be greatly appreciated