How to get in touch with a winner of one of your giveaways

yeah u have to wait longer cause only after 7 days u can do stuff

E-mail, as well as sending through Steam, are atypical delivery methods and will naturally have delays if a GA creator doesn't mention it in their description that they're delivering through those methods. In a case where that was failed to be noted within the giveaway's description, it'd be best to contact the winner through an old giveaway to highlight that fact. Since you did note that in your giveaway, the issue is clearly with your winner [either not having time to redeem, or not being willing to check their email].

Both GA creator and winner have 7 days to send or receive (respectively) a game [ie, up to 7 days where the GA creator can't be needlessly pestered, and then up to 7 days where the win can't be rerolled]. Normally, you'd then put in a Request New Winner ticket (for best results, including a screenshot proving that the key was sent [through either SG or email] and a screenshot proving that you attempted to add them on Steam).

The problem comes in with the fact that you sent a key through e-mail (which, unlike SG, doesn't let you know when it has been looked at). So there's going to be a certain risk with a Request New Winner ticket, and it may be a hassle (or perhaps even an impossibility) to get staff to reassociate the win to the previous winner once you've rerolled.

With that in mind, the few times I've sent through e-mail, I've always sent a test e-mail first, to make sure the winner is receiving the e-mails in a responsive manner. This slows down delivery, but it does mean I can just screenshot any reply [outside of an 'I don't want the key' reply] the winner sent via e-mail as proof for a Request Feedback ticket (after sending a key in a second e-mail) or the lack of response for a Request New Winner ticket.

As far as the best approach for your present circumstance, I'm less sure. That'd be something to take up with staff over the next two days, I suppose. Ideally, your winner'd properly mark the game received before that time.