How is it possible for a Jew to have no heirs (seeing as all Jews are related via Ya'akov Avinu and his descendents)?
Rashi: The Pasuk is referring to a convert who has no heirs. 1
Since a convert is like a newborn baby (Yevamos, 22a).
What does "ha'Asham ha'Mushav" refer to?
Rashi: It refers to the principal and the added fifth.
What are the implications of the phrase "ha'Asham ha'Mushav la'Shem la'Kohen" mean?
Rashi: It implies that, if the owner of the money is no longer alive, then the money goes to his Master (Hashem), who passes it on to the Kohen.
What is the "Eil ha'Kipurim"?
Which he is also obligated to bring after he has said Viduy and returned the principal to its owner.
QUESTIONS ON RASHI
Rashi writes that the Pasuk discusses a convert who has no heirs. We expound "Ish Ki Lo Yihyeh Lo Go'el" (Vayikra 25:26) to mean that he has a Go'el but he does not want to redeem (what his relative sold)!
Moshav Zekeinim: Here we cannot expound otherwise (the heir would not object to getting back what was stolen). Refer to Vayikra 25:26:1:1,2.