If the tenant fails to return the key in violation of the contract and is forced to change the lock and sue, can he ask for rent?

Collect evidence of lessee's breach of contract. If negotiation fails, a lawsuit shall be brought to the court, claiming that the other party shall bear the liability for breach of contract.

The legal basis is the Contract Law of People's Republic of China (PRC).

Article 227 Where the lessee fails to pay or delays in paying the rent without justifiable reasons, the lessor may require the lessee to pay within a reasonable period of time. If the lessee fails to pay within the time limit, the lessor may terminate the contract.

People's Republic of China (PRC) Civil Procedure Law

Article 1 19

Prosecution must meet the following conditions:

(1) The plaintiff is a citizen, legal person and other organization that has a direct interest in the case;

(2) Having a clear defendant;

(3) Having specific requests, facts and reasons;

(4) It falls within the scope of civil litigation accepted by the people's court and is under the jurisdiction of the sued people's court.

Article 120 A lawsuit shall be filed with the people's court, and copies shall be submitted according to the number of defendants.

If it is really difficult to write a complaint, it may be submitted orally, which shall be recorded by the people's court and the other party shall be informed.

Article 121 A complaint shall contain the following items:

(1) The name, sex, age, nationality, occupation, work unit, domicile and contact information of the plaintiff, the name and domicile of the legal person or other organization, and the name, position and contact information of the legal representative or principal responsible person;

(2) Information such as the name, gender, work unit and domicile of the defendant, and information such as the name and domicile of the legal person or other organization;

(3) the request and the facts and reasons on which it is based;

(4) Evidence and its sources, names and residences of witnesses.