My dad has gone missing?

Well, to start off, I'm fifteen and I live with my mum and dad..my dad is like my best friend, he is everything to me, literally, everything. But he has a really bad past, and is an alcoholic, he's not an agressive one, and he only drinks in the house, but lately his past has been affecting him and he's been going out, not telling anyone, turning his phone off and driving the car drunk. Nobody knows where he goes. But yesterday 3PM he went out, whilst my mum was at work and I was at my boyfriends, and he hasn't got in touch with anyone since. I have really bad paranoia, and you can't imagine the things I'm thinking. What do I do? I really can't focus, I can't breathe properly, I've been up all night. Someone please tell me what to do?