Legal Question in Landlord & Tenant Law in California

I assume that your car was parked and someone crashed into it. If that's the case, see if the building has a video of the event. If that's not the case, ask around to find out if anyone saw or heard anything, and investigate. See if anyone neighbor's car has suspicious new dents. If you're at a dead end, so to speak, there's not much you can do, other than to report it to your insurance carrier, and see if you have any coverage for the property damage.