Who will pay for the broken door lock of the building in the property community? Is there a law to solve it?

Yes, but you have many rules to consult.

First of all, property rights, you have to consult the property law to understand that the unit door is shared by all owners of this building, and whoever has something broken will pay for it.

Thirdly, for the definition of property fees, you can refer to the Regulations on Property Management and the Measures for the Administration of Property Fees. You know that when determining the property fee, you can't include the cost of medium repair and overhaul. So, you need to know the extent of this bad situation and the cost of maintenance. The simplest way to judge is to evaluate whether this cost is greater than the total property cost of the whole building owner 1 month. If so, without the support of property fees, this building is all.

Finally, the contract law, you should be clear that the two sides agreed to hire a property company to sign a property contract. Perhaps the contract stipulates that the property is responsible for such projects, and you can make a request according to the contract.