A plant of mine has died.

Of my 3 seedlings in 2 pots, 1 of them has died, the 1 smaller 1 sharing a pot with another plant.

Leaves had been falling off for a while now till hardly any were left, but I was hopeful because a new stem had shot up from near the base.  But, the main stem withered back, and then the new stem fell over, and now you can see a small dead black area at the base of its little trunk, so now the roots aren't getting sunlight from anywhere, and it's all just fated to die.

I have no idea what went wrong, I was hoping that it would find a will to live.