Claiming a personal debt with post-dated cheques

I was persuaded by my friend to put money in an online trading, and he will trade on my behalf and will share the profits.

He guaranteed me that he will trade very carefully and the principal amount will not decrease, but he lost all the money in one night which is AED 35000.

Then he gave me 6 cheques of 5000 each payable after every third month.

Kindly advise how to proceed as he is not ready to pay now.