|Troubleshooting USB device problems including for flash drives, external drives, memory cards.|
See Response 1:
Check that out first.
Rarely, not all the ports on the back of a desktop case may be able to supply 500ma each.
If you have a desktop computer, Note that I answered a Topic on this site recently where a guy had an external drive, which does require the full 500ma, connected to a port on the back of a desktop case - it would not work properly when a webcam was in the port next to it, but it worked fine when the webcam was unplugged. Ports on the back of a desktop case often have two ports connected to the same USB controller module that are ports one above the other - you could try connecting the cable to one of those and leaving the other un-used.
If (a) USB cable(s) came with the external drive, use that(those) cable(s).
In some cases, you need to connect to two USB ports on the computer end.
Once you are using an adequate USB cable (or cables ) and have it plugged into a USB port (ports) that can supply 500ma....
If the external drive is new, it has no data on it.
If the external drive is used and if the data on it has been deleted, it has no data on it.
In both of those cases, it will not show up in My Computer or Windows Explorer until it has been software partitioned (e.g. using NTFS) and formatted.
You do that in Disk Management in Windows, where the external drive does show up.
E.g. Control Panel - Classic View - Administrative Tools - Computer Management - Disk Management.
If the drive does have data on it and you were able to see it in My Computer or Windows Explorer previously but it doesn't show up there now, the data is damaged. See the first link in this post for what you need to do to try to regain access to that data.