How did you stop being French?
Reacquisition is for people who were once French themselves. The way you lost it decides the route: some can be reversed by a declaration at a consulate, others only by decree while living in France. Since 11 January 1973, taking another citizenship has not by itself ended French nationality.
I took another citizenship after January 1973 and never renounced I took another citizenship before 1973 I signed a declaration giving it up, or lost it by marrying a foreigner I was refused under the 50-year rule for families abroad I lost it at independence, by release decree, or renounced it at 18 I was never French; a parent or grandparent was I'm not sure whether or how I lost it