I've missed a submission because my form wasn't confirmed!
That is a very sad thing that happened, either because you forgot to test your single form, or because you have multiple forms and weren't aware of it.
Formspree unfortunately doesn't store submissions from forms before they are confirmed (although this is something planned to change in the near future, the change won't enable us to restore the submissions already lost).
There's really nothing we can do for you now. We are very sorry.