@Nena-Und-Eb0 This is a weird behavior but surprisingly common. There's nothing that you're required to do here, but I recommend sending just one message via Airbnb messenger acknowledging that the guest hasn't been in the home since (date of departure). If the booked period is still in progress, the guest still has the contractual right to return to the apartment. But if it's over, your course of action depends on whether the guest has completed checkout (returned keys, removed baggage etc).
If the guest has removed her stuff and returned your keys, and left nothing damaged - congratulations on 2 weeks of easy income! But if you enter the flat and find the baggage still there as though she was planning to come back, of course you go directly to the police.
Airbnb, in general, has no idea.