Sorry, brah, those are toast!

In post-mortem you will find very little root mass.

We start seed in small containers for good reasons.
A seedling's first and most important job is to grow roots.
When the container is too large there is too much water for tiny roots to uptake.
The soil stays wet and that water goes stagnant.
Without dissolved air, it suffocates the baby roots and your plant looks like that.

There are also soil borne pests and pathogens that give the same symptoms.

Ya got one, slim, chance to save 'em.
Very gently scoop them out with a tablespoon and rinse all the dirt off the rootball.

Then re-pot in a smaller container with new soil, and water lightly with aerated, ph adjusted plain water. (No nutrients).
They could perk up, but it is not likely at this point.

Anyway, that's my take on it.
If you fill out the troubleshooting form, you will get better answers;

http://boards.cannabis.com/plant-pro...anted-one.html

Good luck, you will need it.

Weezard
Weezard Reviewed by Weezard on . HELP!! somebody can tell me what's going on my plant? Hello. i have 5 plant (unknow strain), 1 pineapple chunk, and 1 phatt fruity. and i have trouble with this plant. first, i don't know what this happen with 5 plant (unknow stain). its 3 weeks from sprout, and now almost all leaf yellowing. last i got 9 plant, 4 was die. second, the pineapple chunk and phatt fuity. it's 2 weeks from sprout, i think its so very slowly grow. i'm use 3pcs 18watt warm white, 1pcs 22watt cdl. and 1 x 0.5 x 1.5M grow box. 1pcs ex fan, and 1psc wall fan. temp Rating: 5