Short answer. You can claim the price the heir received for it. If the heir honestly did not know the thing was only being kept for you, the law caps what you can recover at that price, or at his right to collect it from the buyer if the buyer has not yet paid.
What the law says
The depositor's heir who in good faith may have sold the thing which he did not know was deposited, shall only be bound to return the price he may have received or to assign his right of action against the buyer in case the price has not been paid him.
Civil Code, Article 1991 — Heir Who Sold the Deposited Thing. Read the full provision →
What you can actually recover
The article gives you a money claim, not the thing. Where the heir sold in good faith, he is bound to hand over the price he received. If the buyer has not paid him yet, he can instead assign to you his right to go after the buyer for that price, and you step into his shoes for collection. Either way the heir is not required to buy the item back, chase the buyer down for you, or pay you what the thing was worth to you personally. The measure is the price that actually changed hands, so a thing sold cheaply yields a small claim even if it mattered a great deal to you.
This rule shares out a loss between two innocent people
It helps to see what this provision is doing. Nobody here is the villain. Your friend agreed to keep your property. He died. His heir found an item among the estate, had no reason to think it belonged to a stranger, and sold it the way heirs sell inherited things every day. You are out your property; the heir acted honestly. The law has to put the loss somewhere, and it splits the difference: the heir gives up what he gained, and you absorb the rest. Reading the article as a punishment for the heir will only make the outcome feel arbitrary. It is an allocation rule, not a finding of fault.
Good faith is the whole condition
The protection runs only to an heir who sold in good faith and did not know the thing was deposited. An heir who was told about the arrangement, who saw your name on the item, or who was holding your written demand when he sold it is outside the shelter of this article altogether. In that situation the estate is answering as the keeper of your property would have answered, and your claim is not limited to the sale price. Because everything turns on knowledge, what you can show about who was told what, and when, usually decides the case before any argument about value begins.
Prove the arrangement before you argue about money
The practical difficulty is rarely the article. It is proving that the thing was left for safekeeping rather than sold, pledged or given to your friend. Safekeeping arrangements between friends are usually informal, and Art. 1969 allows a deposit to be made orally, so nothing invalidates yours merely because it was never written down. But the burden of showing it still falls on you: messages, photographs, receipts in your name, delivery records, or a person who was present when you handed it over. Raise the claim with the executor or the heirs in writing and early, because an estate that has been distributed and spent is a hard place to recover from.