go on Pokemon Platinum Walkthrough you'll might get the idea.
you use th key in the eterna city galactic biulding between the book case and wall
first you beat the gym leader then fight the Galactic goons and get the Pokedex back the talk to Looker then goto the ware house when you get to the teleporters keep going intill you find a room with three boxes and a Galactic goon and theres 1 poke ball and that's the Galactic key
You find it in the Galactic Headquarters after they capture Azelf, Uxie, and Mesprit.
It is the warehouse in veilstone city.
in the basement of the galactic warehouse in veilstone city
When you go to the galactic building in veilstone' go through the it and you will eventuly find it
In the galactic warehouse to the left of the Galactic HQ
You find it in the team galactic storage area.
in the galactic warehouse
you find it in the galactic HQ
Kick the grunts but and get a key
you get the key from looker and go inside its very simple
The Storage Key opens the Galactic Warehouse in Veilstone City. It is dropped by a Galactic Grunt in Veilstone City after you beat Jupiter at lake Acuity.
get the windworks key, go into valley windworks, and beat the galactic commander. all the galactic people will leave the area
the glantic ware house is in velistone city.but i think you need a key.
you use th key in the eterna city galactic biulding between the book case and wall
you get the galactic key from that undercover officer when he finds it in galactic warehouse or you need to find it in the warehouse or the galactic hq. there both in veilstone city. you will find a item in the warehouse that might be it because i forgot