Short answer. You have a personal action against them for the broken promise, but not a security interest in the item itself. The Civil Code says a promise to constitute a pledge or mortgage only gives rise to a personal action between the parties, since the pledge or mortgage never came into being without delivery.
What the law says
A promise to constitute a pledge or mortgage gives rise only to a personal action between the contracting parties
Civil Code, Article 2092 — Promise to Pledge/Mortgage. Read the full provision →
A promise is not the same as the pledge itself
Article 2092 draws a sharp line between promising to give collateral and actually giving it. A promise to constitute a pledge or mortgage gives rise only to a personal action between the contracting parties. That means the promise does not, by itself, create the pledge or the security rights that come with one. What you are left holding, if the collateral was never delivered, is a claim against the person who promised it — a personal action between the two of you — not a real right attached to the item itself. Delivery is not incidental to a pledge; Article 2093 makes it an essential requisite of the contract itself, on top of the general requirements in Article 2085. Until the thing pledged is actually placed in the creditor's possession, or a third person's by agreement, no pledge exists to enforce — which is exactly why an undelivered promise leaves you with only a personal action.
Why this distinction matters practically
A pledge that actually exists gives the pledgee rights over the specific thing pledged, which matter if the debtor becomes insolvent or if third parties later claim an interest in the same property. A merely promised, undelivered pledge does not give you that. Article 2092 confirms you are limited to a personal action against the person who made the promise — essentially treating the broken promise as an ordinary matter between the two of you, rather than as something that already attached to the property.
The separate fraud scenario the article names
Article 2092 also preserves criminal responsibility incurred by him who defrauds another, by offering in pledge or mortgage as unencumbered, things which he knew were subject to some burden, or by misrepresenting himself to be the owner of the same. That is a different situation from a simple broken promise to deliver — it covers someone who actively misrepresented the property's status or their ownership of it. It does not apply merely because delivery never happened.
What this means for your next step
Since your recourse is a personal action rather than a claim over the specific property, what matters most is the record of the promise itself: how the collateral arrangement was described, any writing or message where it was agreed to, and what you gave up or relied on because of it. That record is what a personal action of this kind would be built on.