For cash / money:
I know you are not US based but just about every state here has a search for property:
https://ouf.osc.state.ny.us/ouf/https://claimittexas.org/etc...
Some states have come together to allow for searching:
https://www.missingmoney.com/en/For the UK:
https://www.mylostaccount.org.uk/index.htm There are also some paid services out there, but I do not know how reliable they are.
For physical items, it's almost impossible in a lot of places.
In the US in most (all?) states if you don't pick up your stuff after a certain amount of time it reverts to whoever owns where it is.
I know in some other parts of the world it's similar.
-Dave
