[Samuel Marks]

The lacie drive is not mounting on the Mac may be because it is not connected well or it has gone corrupted. You can try to use the disk utility to fix it and if the tool is not helpful then format the drive. You can get back the data using a recovery tool. You can get more information at : https://www.macfixz.com/mac-lacie-drive-not-mounting-get-corrupted-deleted-mac-data-recovered