If one can’t find the lender in order to repay a debt, what should one do?

As-Salaamu-Alaikum.
Many years ago I had borrowed a certain amount of money from a friend when
I was working in a foreign country.
I could not repay that amount at that time. Now I have no way of
contacting or even locating that person to repay the loan and it seems that I will never
be able to locate him. I have seen in ahadeeth how important it is to repay a debt. This
is a great burden on me and I keep praying to Allah to help me in repaying it.
If I am unable to find this gentleman how can I ever lighten this burden?
The other thing in this scenario is that money gets devalued over years and the amount of
money if returned now will have a lesser value. Is it enough to repay the exact amount or
add to it taking into consideration the devaluation of the currency. Please advise me
because this is one of the problems I am unable to solve and causing me great stress.
May Allah reward you.