Hi,
This sounds like the recovery partition - do not touch this.
I wrote this earlier ....
Plug the external drive in.
Then Start > type in ......diskmgmt.msc ......Enter
Your external drive will show up here.
You should see G: and one or two extra letters. If the letters are G: / H: / J: try the one next to G: that is usually where the Operating System etc is located.