Are you looking for head enchants for your level 90 character?
Blizzard has decided not to add any head enchants in Mists of Pandaria. They have also removed the Cataclysm versions, both PVP and PVE.
When searching enchanting and inscription from the profession UI, all slots are available except head.
Ghostcrawler has made a post on 30/05/2012, on the us.battle.net/wow forums confirming that head enchants got removed in MOP.
There is also a reason that was given, Blizzard didn’t wanted to force players to grind reputation with different factions that would have made available head enchants once the player had reached exalted with them.