What is the legitimate Islamic solution for recovering the price of land that was sold at the price of building land, knowing that it is agricultural and it is highly probable that the buyer will build on it? And should it be returned to the original seller if the buyer refuses?

If you know that the buyer is purchasing the land to build on it in violation of the law, then it is forbidden for you to sell it to him if the building prohibition is for the public good.

If you stipulated that the land must be suitable for building and then the prohibition became apparent, you have the right to annul the sale and reclaim the price.

If you bought it knowing it was agricultural and did not stipulate its suitability for building, then he is not obliged to release you from the contract.

If its sale is prohibited and you cannot annul the contract, then benefit from it in a way that does not violate the law, or sell it to someone who will not violate it.