I can't play some of my video files. Please help me..?

I can't play some of my videos in my pc. There may be some encryption problem. I can't understand what's the problem is. I've encrypted those video once and then I have setup my windows 7 without decrypted those files. Now I can't play these files. There's said "read error" check this link (http://i51.tinypic.com/rucrw1.jpg) and if i am going to decrypt it or move it or copy it, it shows a mage : Access denied, you will need to provide administrator permission to change these attributes. plz check this link (http://i52.tinypic.com/2qmp89k.jpg). I am so worried .plz help me !!!!