Sorry Claude, I dont read French so its very difficult for me to understand whats going on in the Storyline file you sent.
However, if you just want the Menu page to reset when all missions are complete but the Result is failed, then you can still use the T/F variable method.
Simply create a T/F variable called "MissionFailed", and have it set to FALSE by default.
Set this variable to TRUE at the correct time when the user fails Mission 7.
On your MENU slide, you can have a trigger to reset everything if they fail. This trigger would look like;
Change State of MISSION 1 BUTTON to Normal when the timelines starts on this slide IF <missionfailed> = TRUE.
Do this for the remaining two mission buttons and you now have a working reset.
NOTE - You dont specify whether the user can complete the three Missions in whatever order they want? If they have to do them in order 1,2,7 - this solution will work as is.
If however, you want them to be able to do whatever order they want, then you will need some additional triggers and variables to hold the value 0/1/2 for each question:
0 = unattempted (default)
1 = failed
2 = passed
Is that any better help?