What is in your soil? Seedlings can't take any kind of fertilizers until they are about a month old. Thats strange I've never seen seedlings all fall over like that, maybe one but if they are all doing it then there is obviously a common problem going on here.

I'd just start from scratch, use some generic potting soil and water with Superthrive added to your water about once a week, it's not a fertilizer and will promote root development.