1-Connect your external hard drive to your computer. Once the unit appears on your list, right-click on it. Select "Properties".
2-Click "Tools" in the window that appear.
3-Press "Check now". "Automatically Fix File System Errors" and "Scan for and attempt recovery of bad sectors".
4-Select "Start" to begin the review process of the disc. Check the files after you have finished scanning to see if they are fixed.