What do I do about lost Ball Python?

Hey so I completely understand your freaking out, i too live in a 2 brdm apartment with other units and I once had 3 snakes go missing all at seperate times. but I found all 3. So hopefully thats good news for you. One thing I want to tell you is that they will most likely not be very far from where they got out. I had a baby ball get out and went missing for 6 weeks and i thought for sure she was gone for good but i ended up finding her about 5 feet away from her enclosure. She was hiding in my clothing rack. You need to think like a snake right now. Check places that are warm and safe for a snake, they will try to fit into places that are smaller than their bodies to make them feel safe. So check places you'd never think of checking. My other 2 were adults and they ventured to my baseboard heater which was only 3 feet from where their enclosure is. Just remember, snakes like to feel safe and warm. Good luck and I hope you find it. Another thing you can do is sprinkle baby powder down on the floor in various places you think it may be and if you notice it traced over or moved slightly you know the snake is in that area.