After transferring all of my saved files (pictures, videos, mp3s) from my 500gb Seagate external hard drive to my new Western Digital 2tb hard drive, over half of everything has been corrupted. I don't know why, I am devastated right now. When I first started transferring all of my files to my new external hard drive, I realized I had to format it in order to transfer large files. So I had to go back and copy everything right back to my old hard drive. After I finished formatting the new one, I copied everything back to it. Now not only are most of my files from the new one is screwed up, but most everything on my old external hard drive is corrupt too. Is there a way to fix the files that has been damaged and why did this happen in the first place?