Please Help Me! I Cant hold A Conversation!

I do not know whats wrong with me! I do not know how to hold a conversation. I only reply with small talk. E.g I’m fine, Yes, no. I find it difficult to socialize and express views like others. 

Even in the office, i just greet and pass or ask how is the family? Once they say fine, i may ask how was the weekend? They reply fine and my mind just goes blank. I dont have anything to talk about .

I also stutter when trying express my self sometimes and find it hard articulating a sentence without pauses and mumbling. I feel like a living dead cos i’m mostly isolated. Please what do i do?