There are many acts that could affect ownership. As example, conversion is the wrong act committed where (A) converts to his use, or wrongfully deprives (B) of the use and possession of his goods. Conversion amounts to an unjustifiable denial of the title by an act of willful and wrongful interference. The presence of these ingredients will make liablity even though it was done in good faith and without negligence.
But the remedy in conversion is not given to owners as such. The action can be brought by persons who had, at the time of the conversion, either possession of the goods or a right to possess them, in the later event, whoever claims can be asked to prove his title. It is not sufficient to plead the value of the goods but must particularize the goods in pleadings and prove the conversion of specific goods, as action for conversion against thief after plea of guilty in criminal proceedings.
Conversion may be committed in several ways. Most common is a wrongful disposition, such as a sale by (A) of (B) goods. There may be a conversion by an abuse of a possession obtained with consent. A taking out of a possession of another will be a conversion if the goods are taken without lawful justification and with the intention of exercising dominion over them. However, asportation or carrying away of property without any denial of the rights to possession and enjoyment will not amount to more than a trespass.
IF (A) who has not been guilty of trespass to goods which has come into his hands detains them without any assertion of title, then presumably the detention can give rise to a cause of action for detinue, a wrongful retention or possession of goods or the wrong arises upon a detention of the chattel after demand, apart from any remedy for breach of contract. Detention of goods may be a conversion when adverse to the title, and it is generally a refusal to return goods on demand. Apparently, conversion by detention may be proved in other ways than by demand and refusal, where (A) applied to Court for restitution of goods upon conviction and the application is resisted.
Many may use conversion against interests of others. However, there are legal remedies you should pursue, to enjoy full ownership.