Despite your best efforts disaster may strike. Usually this is because the bin has either been over fed or balanced incorrectly. Also, if the bin has been subjected to an extended period of temperatures over 35C (95F) or below freezing (0C or 32F) the worms may have died.
The bin is rotten and smelly, and no live worms are present
It is important to remove any rotting food from the bin as the anaerobic (oxygen-poor) conditions make it impossible for the worms to live. Remove all the rotting food from the bin and set aside. Keep any live worms present in a separate pile to reintroduce to the bin. Once all the rotting food is removed, add a layer of fresh bedding material and any live worms you have recovered. Add shredded paper or cardboard to the bedding to promote even better aeration, and to balance any excess nitrogen causing the rotten smells.
If there are very few worms left, you may need to purchase or harvest more live worms. Restart feeding the bin as normal. It will take some time for the worm population to recover if a large proportion of the worm population has died.
The floor was removed too early to harvest castings and contents have fallen out the bottom
The tapered shape of the hungry bin compresses the castings as they move down through the bin. When the floor is removed, only the castings at the very bottom of the bin should fall out, as the remainder are held in place by the shape of the bin. If the castings in the bin are not sufficiently compressed when the floor is removed, some, or all the material in the bin will fall out. Usually this happens because the floor has been removed too early, or before the castings or bedding material have become compressed.
It is also an advantage to allow the bin to become full to the top with finished castings before removing the floor. A full bin is less likely to have problems as the volume of the castings helps moderate the bin, and prevent problems.
If the contents have fallen out completely, reinstate back into the bin in the same order that they came out of the bin, with the oldest material to the bottom, and the live worms at the top.
If only some of the material has fallen out, but the majority of the castings are still in the bin, replace the floor back onto the bin, and simply return the castings that have fallen out to the top of the bin. Placing finished castings in the top of the bin will not affect the worms present in the bin, but you may need to wait for the worms to migrate to the surface again before you can feed the bin at full capacity.
The bin has fallen over and the contents have fallen out
Get the bin back into an upright position. Reinstate the material that has fallen out – in the same order it came out in if possible – with finished castings toward the bottom and live worms on top. You may need to wait a few days before feeding the bin again as the worms will not all be present at the surface of the bin.