Christmas season escape

Yesterday, in honor of the new year, you had a party at his apartment, which took a lot of fun and vigorous. But in the morning you are faced with three problems: 1. you have a headache. 2. chaos in the apartment. and 3. I (the most important problem that urgently need to solve) one of my friends, accidentally or not - it does not matter, you locked in his own apartment. Find the key to get out, he's out here.