Excel document suddenly won't pull up. Flashes and disappears.

I was working all morning on two Excel sheets and suddenly, one of them would not pull up except a quick display in a tiny box for a nano-second, and then it disappeared. I've restarted my computer and check for similar prolems with no positive result. I am actively working on this and need to get to it. All the other Excel files and every othe kind of file come up fine. I've tried through Excel and also through Finder with no luck. Thanks!