R Avrohom Ehrman (The laws of interpersonal relations, from p. 399) has a chapter devoted to the laws of returning objects. The summary is that sales are final unless the seller willingly accepts the item in return, and the buyer is forbidden to pressure him to do so. In your case, you are permitted to return the objects but would have to tell the seller what happened and see if he is willing to accept the return.
Specifically, R Ehrman writes
- To "reverse" a sales transaction is, in reality, to perform an entirely new transaction, in which the item is actually sold back to
the original seller
- This new sale is like any other transaction, both parties must agree to it, and each one is forbidden to pressure the other to
conclude a sale against his will
- If the prevailing practice in the locality is to accept returns, or if the parties make an explicit agreement at the time of the sale to
allow returns, then it is permitted
He then lists a varies of reasons one could return merchandise (e.g., defective merchandise, mistaken amounts, damaged food products)