ME3 original how to backup achievments?

Hello, I had all ahievments unlocked, then reinstalled the game completely (with removing bioware folder with saves), BUT I launched it only later when EAapp was in offline mode, this led to all my achievs was black (locked). When I launched it in online mode, I restored my galactic readiness at 100% but still all achievs was locked and now I have to redo them.

Can you tell please in which file they are stored so I can backup them for this case?