Disappeared Map on Neatline


I was trying to readjust the zooming setting for the map I am customizing in. After saved the last record I added, the map disappeared. I get a blank page without any menu on the left-end so no possibility to go back to the settings.
Is there anyway to go back to a previous version of the map ? Some type of history backup ?
This is a year-long work…having it vanished now would be devastating.