2000 Hyundai sonata there is a black box under the car in back on driver side trunk it has come loose and need to get strap but you have no idea what called any help?

That black box under your 2000 Hyundai Sonata is most likely the charcoal canister. It's part of the evaporative emission control system (EVAP) and stores fuel vapors to prevent them from escaping into the atmosphere. It's common for the straps holding it to break or come loose over time.

To get it re-secured, you'll need to find replacement straps or possibly some sturdy zip ties. A local auto parts store should be able to help you find appropriate straps or fasteners. You can also describe it to them as the "charcoal canister" or "EVAP canister" to ensure you get the right parts.