Legal Question in Landlord & Tenant Law in California

If you informed the landlord that you have surrendered possession, removed all of your belongings, and just couldn't provide the keys, that should be sufficient. I would suggest explaining in writing what happened with the keys and your offer. Send it certified, return receipt, and keep a copy. Then, the landlord would have no basis to sue. If he doesn't take you up on the offer, that would be his tough luck. Your defense would be that you offered to replace the locks at your own cost, but the landlord was unreasonable.