In general, if you format a drive but do not use it afterwards, there is a good chance to get your data back. In order to restore drive's original state in Disk Management, I recommend you to enter Device Manager and uninstall the drive. It should appear under USB devices. Restart the PC, plug the drive back in and wait for the OS to install the drivers. If the drive keeps being recognized as an internal drive, enter Disk Management and right click it. Remove its drive letter. Eject the drive and reconnect it. Any change?
Hope this helps