Also recall that when you exit the scenario editor that
a backup is made in slot 999. So you
may have an older version of any maps etc, sitting in that auto-save slot.
It is mainly for that
oops moment when you exit the scenario editor and then realise you had not saved your edits
,
but you can always load that save slot into the currently open editor as a "restart", before exiting what you have just messed up (or that will go into 999!),
provided that it is an older version of the same scenario you were working on.