Remove the mattress and the box spring, exposing the bed rails and the headboard. Step into the center of the bed frame for the best access to the metal ends.
Lift up one side of the bed rails near the headboard. The metal hooks should slide up into the slot in the headboard's leg. Pull the metal end and the headboard apart. Repeat on the other side. The metal rails should now be separated from the wooden headboard.
Unscrew the nut from the bolt holding the metal bed hook adapter bracket. Remove the bolt and take the metal end off the bed rail. Repeat on the other metal end.
Align the replacement metal bed hook adapter bracket with the bolt holes in the bed rail. Insert the bolt and tighten the nut with your fingers first, then a wrench. Put the second hook adapter bracket on the metal end of the bed rail on the other side.
Align the metal hooks with the slot in the headboard leg. Insert the hooks, then press firmly down until the hooks are secure against the headboard leg. Repeat on the other side.
Set the box spring and mattress back onto the bed rail.