I won a giveaway

this sounds like a difficult situation. if support can't make him understand what reroll means, maybe they can give you a special permission to regift the key? because rationally, that's just "rerolling" it for him.

What ever you do, don't contact support.

Eat the key, and do be afraid to use mayo!

Tell him how to reroll in that case.

If he's not that good with the English language, you could invite someone with his native language into a Steam group chat, so that he can translate it for you.

If that still does not help, contact support.

I recommend purging it with fire.

That's definitely a problem with the RNG, I've had it happen twice in the past (considering I've won 10 times, that is insane). Thankfully in that case, people were sending gift copies and I could just turn it down.

Contact support. I had the same problem like you.
They said to contact the giveaway creator.. but no answer received back from him. So marked as not received.

I suggest you to make a giveaway for that. Its simple.

Give him directions, like "Go to http://www.steamgifts.com/manage/created, click "Gift Sent", Request New Winner"

If he doesn't do it, mark it as not received after 7 days. That usually does the trick.

"WHAT HAVE YOU DONE!"

i think you should just teach him about what it is a reroll i don't think that could be hard

He tries to set you up, and when you regift it he'll report you. XD

Like TheDopeFish said, ask his nationality, then you can find the basics to explain him the situation.

Ive had that happen, the gifter just rerolled, no issue, no problem.

Halps you!

rerolls dont need staff approval?