Find a drive in Device Manager
All LaCie drives appear in at least one place in Device Manager.
To access Device Manager, click on "Start" and select "Run" from the menu. In Windows Vista, the 'Run' option doesn't appear by default, so press [Windows-button] and [R] on your keyboard.
Enter the command:
devmgmt.msc

Click OK and the Device Manager program will open.
For troubleshooting look in the "Disk Drives" section. It might be necessary to click on + on the left side. It should appear like this:

In this example, the disk drive inside the LaCie case is made by Toshiba. This can differ from drive to drive. If it is difficult to identify the drive, first unplug it, then reconnect it. The entry that changes is your LaCie drive.
What is the situation you are facing?