What is the ruling concerning the devices that remained with my husband and that Toshiba company did not request back after the contract ended, and what should he do with them, knowing that they are old and cannot be returned?

It is not permissible to keep devices that have not been authorized for possession and use, based on the Prophet's (PBUH) saying: "The hand is responsible for what it takes until it returns it." The remaining devices must be returned to their owning company, unless the company authorizes him to benefit from them or possess them for a specific price.