although it's not yet clear to me whether you have actually 'won' the auction or not.
2 cases i could think of.

1. ebay says you are the winning bidder and up to pay
you can pay ahead and claim yours. seller is due to ship it to you regardless whatsoever the situation.
2. auction ended, and you are not listed as the winner
nothing much you can do, but also you are not at any due. no obligation.

common things here—i've been selling/buying on the 'bay for long time too.
– there's no way to 'accidentally' close the auction.
it's usually the seller feels it goes cheaper than he thought and try to end it.
you can easily do that marking as 'the item is not available any more' sorta statement. stupid ebay sys.
– even though the seller wants to end the auction early, he/she can't just do it if it's close to the closing time.
(this is where my confusion is from)

anyways,
in case if you ever are left as 'unpaid' buyer, you can simply claim through ebay.
have all the communications w the seller attached—they are gonna review them on their end anyway, but it is important to show ebay that you know what you are doing and you have things needed to support the argument.
ebay is usually on listening manner and solve it reasonably, but not in the fastest manner.

hope this helps.