@Auspice Is your instructor giving you a final of F, or is the mark of F a placeholder until you show the actual work?
Most things done online will show times/dates of last updates. In theory, if you can file an appeal with the prof under the grounds that the system you were using locked you (and her) out of the project, though it was completed.
My cynical experience dealing with post-secondary education is this: if you appeal, you'll almost certainly win, especially if you continue to appeal it all the way up the chain. Eventually you'll get to someone who believes you shouldn't fail students because it gives the sadz, and you'll get the chance to show them your work.
Additionally, if you present information that describes the locking out phenomenon happening to other people (articles, etc), then the prof should be willing to at least hear you out.
I wish you the best of luck, though. Failing because of something outside of your control - and outside what a reasonable person could foresee happening - is awful.