First of all you have to dhukuti is an illegal business. I don't think you have any proof that you have given some sort of money to your so called friend. So there is nothing you can do legally. But you can still go to police/court and complain about him.

@Furke - Why do you want to know about dhukuti? Are you planning to run this business?
One of my neighbor had this business when I was in Nepal, so I am trying to recall and put here:
a) If you are planning to run a dhukuti, you are called 'GHOPA'
b) you will make one group of dhukuti members(generally that can be 10 -20 persons)
c) you will make a plan to collect same amount of money(i.e. $1000/person )
d) Generally ghopa charges 2-5% facilitation fee.
e) There will be bidding every month to get the money except first month. As a ghopa you will take all the money in first month.
f) There will be highest bidding(i.e. highest minus) from second month, if highest bidding is $1500, then one gets 10000 - 200(ghopa fee) - 1500 = 8300.
g) now every member will have to pay 8300/10 = 830.
h) in this scenario, this person will get 8300 - 830 = 7470.
i) this goes until each member gets ones chance.
j) Whoever goes till last, he/she will make some profit.

These are the points I remember, so I am hoping you will get some idea about dhukuti.