What does it show when you find it in Windows Explorer? If nothing, go to Control Panel>Administrative Tools>Computer Management>Disk Management to see what that has to say.
If it says the disk needs to be initialised or formatted it, back out and disconnect the drive using the safely eject procedure.
Download a version of Linux - Cinnamon Mint is a good one for starters. Use a utility named Rufus to combine it and make a memory stick into a bootable flash drive.
Set your BIOS to boot from the USB device and once the system completes its opening ceremony, connect the external disk and see if the file manager can display your files and recover them to the laptop's hard disk.