Just like the French Revolution, except I'm willing to put these heads back on. Shocking and disturbing, but surprisingly common, headstock breaks are very repairable!
Your headstock might have broken after a fall or bonk, or maybe you found it smiling at you though no obvious harm came to it. The grain structure of the wood at this pivot point in the neck is under extreme tension, and it doesn't take much to split the wood there on most instruments (though some are more notorious than others...).
headstock is splitting at the neck joint
perhaps a fall or a collision took place
headstock is completely separated (full decapitation)
Guelph Guitar Repair is your home for headstock repairs. aka: re-capitations