Hello,
I recommend you try some basic troubleshooting:
1- Disconnect the drive from the computer and restart the computer.
2- If the computer is a desktop, connect it on the back USB port (directly to the computer, not through a hub).
3- If possible try another USB cable Or another computer.
4- Go to "Disk Utility” to verify if the drive shows up there.
If the drive shows up in disk utility but it is not seen on Computer, then it means the partition is corrupted and you will have to format it in order to use it again. Please note that formatting the drive will delete all data stored on it.
