Bad at Contributing to Conversation - Comments

When people make statements like that I usually just make a reasonable assumption, even if it sounds dumb, like "oh, that must be tiring?" or "you must be sleeping really weird hours then?" and add a cheeky q mark on the end there to prompt their further response. He might come back to you with "yeah, I only get __ hours of sleep" or "yeah, I sleep throughout most of the day lol". Then you could tell him about how your work/study is going if you want to keep the conversation flowing coherently.

Think of it like a tennis match. If you can ask them a question then the ball flies out of your court and back into theirs.

Also, don't be afraid to be random or change the topic with a random statement of your own!
It can sometimes spark an unexpectedly good and lengthy conversation. For example, if I'm multi-tasking and watching a TV show while on Facebook, I might have just watched something dramatic like a sudden murder; so I could say to the person I'm conversing with on FB: "wow, this show is intense!"
Then I'd assume that they'll respond sooner or later with "what show are you watching?"/"why?"/"lol, what's happening?"
That allows me to tell them about the show I'm watching which then allows them to tell me if they have or haven't seen it before. Then I could ask what kind of shows they do watch, if any, to find out if I've seen any that they've watched.

I also find that an easy way to buy more time and possibly prompt them to add to the conversation again is to downplay myself, (possibly adding in a joke aimed usually at myself or an inanimate object relevant to the conversation) or to compliment them. I might say "oh wow, I couldn't do that", "really? You're brave, I'd run a mile" or if we're having a conversation about football I would say if asked my opinion on it: "I just watch it for the commentaries; they can be hilarious sometimes. One commentator repeatedly called out "Kaká" and I thought he was trying to imitate some type of bird call."
It's not really that funny, but it's a neutral enough joke just to prompt them to laugh (through politeness or flow of conversation) and then the ball's back in their court again.

Hope this helps! I have those awkward moments too, I think everybody does but to different extents. Just remember that people aren't expecting you to be a conversational whizz!

@losing control: I always end up saying "cool" and then cringe after I send it. I actually almost did that, oops lol.

I have that problem to, I'll end up accidentally ignoring to people because I can't hold a conversation to save my life.

I would just say something like "oh I see, how do you like working nights?" or something, and then go from there. But I'm super awkward so