A break-in is violent even when nothing irreplaceable is taken. The French system is actually well organised — if you follow the order below, you protect both your home and your insurance claim.
If you arrive and the door is forced: don't go in alone if the burglar could still be inside — call 17 (or 112). Even after the fact, avoid touching the lock and the entry points; the police may take fingerprints for serial burglaries. File a complaint (plainte) at the local commissariat — you can start it online via “plainte en ligne”, but the paper récépissé is what your insurer wants.

An emergency locksmith secures the apartment the same day: temporary lock, boarding if the panel is damaged, full replacement if possible. Keep every invoice. This step is covered by many French home-insurance policies as “mesures conservatoires” — reasonable emergency costs to prevent a second intrusion.
Statistically, burgled homes have an elevated risk of a second attempt in the following weeks — the intruder knows the layout and the weak door. This is the moment to move to an A2P 3-point lock, reinforce the door, or install a certified armoured block. Your insurer may even require an upgrade to maintain coverage — and often your premium improves with certified equipment.

Change what needs changing, then reclaim the space: most of our clients say the apartment “feels theirs again” once the new door hardware is in. That's the real end of a burglary.
One call in English — a fixed price — a technician at your door in ~30 minutes.