Client Not Paying Salary

Hi,

I am writing with a heavy heart. A famous US author (won't name right right now) with over 750k followers is not paying me.

They did the same thing last year, but after a year they contacted me, did a huge apology and paid me my due and also increased me salary from $300 to $1000 a month. I was employed last September. Sept - Dec everything went smoothly. They didn't pay me for Dec, gave an excuse and I had no other option than to wait.

He said I'll get paid this Monday but nothing. Now they've removed me from Slack channel. I am guessing they're again running.

I only have his number and city. What can be done? I am not from the US.