This is how I got mine working
1) click start
2) right click computer and click manage
3) left click disk management
4) Your external hd is probably black and you should recognize it by the size. Is Disk 1 if you only have one other hard drive.
5: right click on the black bar.
6) here you may be on your own. I believe you left click on extend volume.
I know it is vague at the end but My hard drive is working and I do not want to lead anyone where data would be lost.