k, computer broke, sent it to HP, got it back, activated it. Got a virus, used the partition part of my disc to redo windows. now it says my product key is invalid for activation!! What am i supposed to do. i only got 4 days left to activate!

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Contact HP first (try their online tech support, it's fast and so far I've been very impressed with it).
If for some strange reason THEY can't help you, I'd contact Microsoft and explain your situation to them.
One way or another I'm sure you'll be back up and running in no time.
Good luck.