Do you mean that you can't remember if you submitted it this week or for another topic? If it's for this week, Deb will be able to help you.
However, if you wrote it before the challenge prompt, then it's not eligible for the challenge since you're only supposed to write new material or totally rewrite something old.
It's one of those rules that people forget about and I've seen a lot of people do it. A good way to remember is the challenge is to help you write more often and write to topic.
I have taken stories that I've told aloud but never written and used them for the topic which is great because otherwise I would never have written them down. Since storytelling can change with each telling, by gearing the story to the topic, I am rewriting it and often will end up with something quite different.