What should I do with 50 riyals that I found in a public park, and I feared it would be lost? I cannot identify its owner in nearby stores. Is it obligatory to announce it for a full year, knowing that searching for its owner seems difficult and impractical?

If someone finds a valuable lost item (luqata), they must announce it for a year in its original location and in public gatherings. If its owner comes and describes it, it must be handed over to them. It is not permissible to benefit from it before the year has passed. If one benefits from it, or intends to benefit from it before the year, they become responsible for it (liable for its value).