Apparently the Trade Depot and Still were made out of ice and melted. Sorry for the accusation DD

Also yeah the problem is, even if you fix the drink problem, the Dwarves are so enraged by both the fact their friends have all been left to rot, and the smells of the miasma from the rotting corpse themselves that they are permanently miserable. Cue further upset from friends and pets being beaten to death by angry Dwarves and you have an unsolvable problem.