what should i do if the winner actived my giveaway game in steam but no Respons in SG

Contact support.

Gather proof (screenshots) and make a support ticket.

^ Sounds like good advice, hope I don't get in a situation like this, anyways good luck :D

I have a friend with this very same situation, but the winner's profile is private, so he can't see if the game (a key) was redeemed or not, and it has been over a week since the giveaway ended... (and the game was BioShock Infinite for a Group giveaway).

thanks for comments.i will take his steam profile screenshots and wait for another 3days,if it's still Awaiting User Response i will contact the supports.thank you for you all.

Just try to talk to him rather than waiting to see if he does it on his own. Maybe he's just ignorant of how it works?

Same happened to me, happened MORE than a week ago, and might I say, he hasn't confirmed it yet...