Deductions & credits

Hi 

Thanks to all those who contributed to a question from geauga. In this post, I will give further clarification of my initial post of last year. 
Before taking up tax residency and citizenship in USA, I had some fixed deposits in foreign currency.  Since then, I went on getting them renewed after every 3 years.  At the end of each year, I went on paying taxes here in USA on interest incomes on those deposits.
 I have now closed some of my old deposits and got proceeds here in USA. 
I notice that proceeds my original deposit of say $100 (converted from foreign currency in US$) in year 2000 is now reduced (after earning 6% to 10% compound interest in each term)  to $75 in 2020 because of depreciation of that foreign currency.    It means loss of $25 in capital plus US taxes that I paid during the last 20 years on that deposit.   Here are my questions:
1.   How do I calculate capital loss of a fixed (term) deposit because of depreciation in a foreign currency? 
2.   Where do I report capital loss in schedule B? 
3.  Any other suggestion. 
Thanks again, geauga