when a plant gets stressed it takes about a week give or take to recover and start growing again. That plant looks very stressed. You need to pin point what the source of the stress is resolve the problem and give it time to come around.
Go back to the basics, temp , light/dark , ph, wtaer and nutes (which it doesn't need right now but will eventually)
If all these thing are working together the plant will recover slowly.
If you have more seeds, I would start from scratch and make sure you do it right, listen to the grower on here. Your new plant will out grow that thing in no time.
Just my two cents