I'm afraid that is will be a problem for Particle to resolve for you... AFAIK, Digistump doesn't have anything to do with their backend stuff.
All I can suggest is that you try lodging
a question on their support system under something like Software -> Console -> Unable to log in, and see where that leads you. You could also post something
on their forum, but you'll need to create an account if you haven't created one there already, as it doesn't share the login details with their other services.