axle peice broken

[BluCivic00]

i was driving my car and realized my back left wheel wasnt gettin power and i looked and the little peice... tryin to think of how to eplain it, ......its like the part that comes from the axles has two parts that stick out on opposite sides, and the part it connects to on the wheel part had to slots for those and thats what enables it to get power while the suspension is flexing. im not sure if i can fix that peice or if i should go to rs and order a new one or just trade in the whole car for a new one, i dont even know what its called