Recovery Issues?

I have an external hard drive that once belonged to my acer windows 7 desktop.  I bought professional recovery software and was able to recover various jpeg images, and word (2003) files.  Although the previews of these files show up in the recovery program, when I transfer them to my laptop, they're no longer useable.  I've tried various programs and decoding (blah blah), but none of my jpegs will open with anything, and all of the word documents continue to show up as a mass of useless characters.  How come the previews were fine but I can't use them now?