does your hard disk open after inserting it to the computer?
sign in a particular account in linux.insert the hard disk and try copying files.
if it does not work, then try formatting it in vfat by the command
mkfs -t vfat /dev/sdb1
replace sdb1 with the device name given to your device by your system.
do this after unmounting your hard disk(right click on the hard disk, select unmount).