Adding onto this, be sure that you haven't given out your password or account details to anyone whom would be able to edit/delete your characters in any way. I'm not too certain how recently you had checked the game without the patch to see if the characters were still there, then downloading the new update, but if you haven't been on the game in a while, leaving account info in the wrong paws may not do you much good. Also, do you have any other accounts? It's possible that you actually created those characters on an alternate account, rather than the one you're logging into.
If all else fails, I would try giving the re-install a go.