Am I obligated to return what I stole in my childhood and youth, such as food and toys, and does my inability to reach the rightful owners prevent my repentance?

The door of repentance is open until the sun rises from the west. The thief must offer sincere repentance and return the rights to their owners. If he does not know them, he should give charity on their behalf equal to the stolen amount. If he does know them, he should return the rights to them without informing them of the reason or mentioning that it came from him; rather, he can send it through someone else. Abandoning prayer is one of the greatest destructive sins.