I've forgot how to talk. i can't hold a conversation no matter who it is, because i can't put sentences together and it comes out really forced.

Expressive issue?: If this is accurate, you have what sounds like an expressive aphasia. There are many causes. If true, you need to speak with a neurologist or an expert in speech pathology. Based off your additional patient information, there are negative symptoms in certain mental illnesses which may make speaking difficult. If the neurologist and speech folks rule out those things, seek a psychiatrist.