What happens to funds in forgotten or unclaimed bank accounts?

In most cases, after “X” many years (the number varies from country to country), the asset balance is shifted from the bank to the central bank. The central bank will keep custody of these funds, literally for eternity, unless there is a provision to destroy the balance or assimilate the balance after say 50 years.

Should a valid claim be made for the money, the central bank can very easily recreate the balance and hand it over.