I was moving files from my computer to my external hard drive when my computer mostly froze. I was able to 'restart', but nothing actually happened. I canceled the files from moving to the external, but they never really canceled. I ended up turning the computer off with the button on the laptop. Now, it fails to read all the files on the hard drive. When I go to 'safely remove hardware', it says the external is in use when I'm not using any of the files. How can I fix this?