Oh gosh, I'm so sorry your little one is missing
I will send out good thoughts that wherever he is, he is safe, warm, and fed, until he can get home to you. Hopefully whoever has him (hopefully someone does, at least he's safe if that's the case) will realize that keeping him is wrong and will make an effort to locate his true home.
Good luck, and keep reading here. There are some great tips on how to find a missing dog, and lots of caring folks that can "hold your hand" until your baby is found, and beyond
Hang in there!!!!