I recently became guild master of the thieves guild. But cannot get the achievement until i trade in my thieves armor. Problem is i don't have it anymore and have no idea where it is or if i can even get it back. Is there a way i can get more of the armor or am i just out of luck and have to start over? Im also on xbox so no console commands for me.

Save before, trade in armour, get achievement, reload save.

Simple.

That will work even though i dont have the armor since the second quest for them and couldnt upgrade from there. and thats what missing i dont want ot have to redo the quests unless i absolutely have to.