mint, fenugreek plants

[ga_2004]

Hi all,

I had sprouted fenugreek seeds and planted it in a pot with moist soil. The seads spouted to one pair of leaves and remained for 2 days. later the third day I saw the from the root the stem got black and similar with the other and all died. I made sure the it was in a sunny spot, soil was moist enough. Can anyone pin point what went wrong. Even my mint showed the same sign?

I stay in Singapore where wheather is humid and warm