loose axle nut now what

[96yukonGT]

Well for christmas my dad had a guy install a cv shaft in my 96 yukon since i wore it out doing snow removal for his lil business. but the retard didnt torque the nut down and i herd it poppin looked down and it was wobblin. so on the side of the road i tightened it back down but i little silver cylinder lookin piece fell out. Dont know if its some kind of bearing or a spacer. its only like 3/8" long and now my wheels locked up. what do i need to replace now. Merry christmas to me.