Hi Blox. I'm Greg, an installation specialist and 9 year Windows MVP here to help you.
Access the Command Prompt to run Disk Check on the drive:
https://www.groovypost.com/howto/check-hard-dri...
If it won't run or help then run DIskpart Clean All command to wipe the drive:
http://www.sevenforums.com/tutorials/52129-disk...
Then see if you can reformat in Disk Mgmt:
http://www.wikihow.com/Format-an-External-Hard-...
If it won't repair then replace it.
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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