Customer vanished after work had been submitted

I completed my freelance proposal for the customer(Mulla Zone). They were really happy with everything I had done. I finished the job, submitted it and then they completely vanished! I've tried through PPH, Emails, what's apps and phone calls but nothing. It was my first experience as on here, so I'm really disappointed. I wasn't aware the customer had to accept the proposal first, so I haven't even had a deposit. I did the job in good faith after speaking with the client. Such a shame there are such dishonest people out there.

Not sure what to do now?