What can I do about an extra movie ticket that I bought ALONE and is now sold out?

So I bought a midnight showing ticket for Harry Potter and the Deathly
Hallows Part II, at 12:03, about a month ago. I've been telling my
friends to do that as well before the tickets sell out, but
unfortunately as is always, the tickets sold out for that showing and
it's too late. There is still only ONE showing that isn't sold out,
which is at 12:02, and one of my friends says that she'll buy her
ticket today. So I don't know what I should do, buy ANOTHER ticket,
try to sell the one I already have, or just go alone, which I really
DON'T want to do. So, what do I do?