How to report loss on cancelled stock options

Hello,

 

I exercised common stock options of my startup company in 2017 where paid some big amount of money.

In addition to it, I paid taxes on total exercise gain when filed taxes for 2017.

Then in 2018 the company was acquired and all common stock options were cancelled.

What form(s) I need to use to return my money?

 

Thank you very much!