Two of the three icons of the drive's partitions show on the desktop. One has disappeared and the contents are not accessible. Right clicking on the desktop icon of the partition gives the option to eject. Then the error message shows that the drive is busy and cannot be shut down. The drive is continually pinning. Kindly advise if possible how to safely remove the drive. Can the lost icon of the third drive and the datd contained in it be found, please? Kind regards
If you click on one of the partitions in the unity launcher, you can select "safely remove parent drive". Wait a moment for any data to be written out. If the device automounts again after a few seconds then repeat this operation and you will be able to remove the device.
If this is an earlier version that does not use unity (or does not have the remove device functionality) You can unmount all of the partitions in Nautilus (filemanager) or with the umount command line and then it will be safe to remove the device.
Remounting partitions after they have been unmount is a different question, and you may not be able to access the device at all if you have used the "safely remove" option, until you remove the device and re-insert it again.