How can I say things I want to say out loud?

i’ve been struggling with speaking to people first. It’s bothering me a lot because I want to get to know to people but it’s like my mouth doesn’t want to open. I know what I want to say, but my mind just stops me from actually saying it so instead I sit in silence. I don’t understand myself. Sometimes i’ll talk first and ask simple questions but other times I stay silent and not because I want to. I want to talk to people, but i can’t cause my mind won’t let me more than half the time. I really want to break out of this silence trance, but I physically cannot get words out my mouth. I’m so frustrated with myself. I feel like i’m missing out on so many potential social connections.