Hi Oephaelia, I have an old friend who has had his troubles with crack and heroin. I am also friends with his brother and I will get calls from the brother once in a while asking if I know where Dave is because things are missing from the house and he can't find him. He'll call most of Dave's friends and if no one has heard from him, it usually means he is off on a binge somewhere. He will disappear for days with no contact, then reappear out of no where when he has run out of money.
There is a good chance your brother , given his drug of choice, is off using. I know my friend goes to dingy hotels and smokes crack until he's blown whatever he got for stolen items at the pawn shop.
A drug user on a crack or heroin binge aren't likely to pick up the phone. I am sure your brother will turn up eventually. They always do. I am sure you are sick with worry. Feel free to reach out here for support.