if you uninstalled it and no longer have your key then you will have contact the manufacture and see if they can give you your key - if you can provide proof of purchase.
If you cannot provide proof then you will have to purchase another copy.
Like sobeit has said, we cannot help with this, you'll need to contact the publisher. Though you shouldn't have to - the CD-Key should be on the back of the game manual or inside the games' case.
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