Lock-out is a crime pursuant to Connecticut General Statutes §53a-214. If you have been locked out-call the police. I've also included a link to the judicial website that has a very friendly guide for other issues, below.
This is general advice and does not establish an attorney-client relationship.
It is illegal for your landlord to lock you out of your apartment when you have the right to be there. You should: 1) Demand the new key from your landlord. If s/he refuses to comply; 2) call the police and tell them that you have been illegally locked out of your apartment (be prepare to provide proof to the officer that you have the right to be in your apartment e.g., court order. 3) Go to the housing court and file a lockout suit. Generally, landlords comply once the police are involved. However, you may still file a suit against your landlord. The penalty for an illegal lockout is contingent upon the court's assessment of your damages.