How do you deal with unresponsive clients?

[#1]

Hello y'all. Hope you're doing great! 

I needed some suggestions in dealing with clients that are not responsive. So I'm currently working on a project which is basically making a very short 4-6 slides deck. The client gave me the basic idea of the content, the color themes and all. But he didn't give me full brief and he doesn’t answer my questions. He seemed nice when he sent texts but for some reason, he just says things he need to say without answering the questions I might have. He set the deadline 15 days later just for the first draft for a task that might require just a week max without consulting with me. I've been asking if he has any requirements or detailed brief or if he wants me to start working on the deck already for three days but he didn’t get back yet.  I asked him for any email or WhatsApp if he is not available in Upwork for the communication. 

How should I deal with cases like this? What if the client just ghosts me overall? He funded for one milestone.

PS: He took my interview 20 days back and hired me after 20 days. Can he be just a laid back person who takes time with everything?

Thanks for your response. 

[#2]

Just do whatever you can with the instructions you've already been given. It's not your fault if you can't make the deadline when he hasn't told you all you need to know. This happens a lot with clients, they hire you and then disappear for ages, sometimes forever. That's why it's essential to get all the details you need when they first contact you, so you can do the whole job without any further input from them.

[#3]

I actually did ask for all the details the very first time and he was supposed to get back with more details soon. But he didn't. But the details that he gave is probably good enough for a draft pitch deck even though it's not enough for the final pitch deck. So I'll submit that the draft within due time and request the payment I guess. If he doesn’t contact further, I guess I'll get the payment after 14 days eventually for that first draft. 

Thanks for your response Robert.