ok first, be calm....smoke a bowl.

She's not gonna die today on you. Marijuana is a hardy plant, it takes some doing to kill it. It's a weed, it wants to live.
Ok, now you said you haven't added any nutes. Why? You also said they are turning yellow. The three key things you need for healthy green plants is Nitrogen, Phosphorous, and Potassium (these last two nutes are what helps keep her green). So, you need to go get yourself some nutrients asap from the grow store. And I'm not talking miracle grow!! Since you're a soil grower and I grow hydro, I'm not sure what brand of nutes you should buy or how much you should use. What ever you end up getting, don't go crazy with it. What I mean is, don't keep adding more nutes each day just because your plants aren't nice and green the day after you added nutrients. It takes time for the plant to respond to any changes we make. And get a pH meter. You need to keep your pH around 6.0 for soil, I believe...
Can someone here suggest some good soil nutes and how to use them, please?
if no one suggests anything, then go check some of the soil growers threads on nutrients and see what they are using with good results and copy what they do... that's the best I can offer. Good luck.