Easier to reload a save before the headless glitch.
However to fix.
Drop everything (that you can). Including equiped items.
You the following console command
player.recycleactor
Pick up your items, equip armor.
Note: This issues is caused by using TGM/TIM and 'dying' due to a death animation (e.g. decapitated by Deathclaw). You won't die but the game still removes your head.