I reinstalled windows on the laptop of my daughter. Before doing this we made a copy of her music, pictures and so on on an external drive which was formatted in NTFS. Unfortunately, the folder we created for the backup was empty (I checked after I reinstalled windows). Today a miracle happened, as suddenly the data were back but when I tried to copy them to another place they disappeared again. Checking the external drive with disk utility I got the message "filesystem is not clean". Is there a way to recover the data? Preferred solution would be a tool with a gui. The drive I need to repair is formatted in NTFS and is connected via usb to laptop.