I know liquid diets aren't the healthiest, but I'm desperate. will this work?

Don't use soy. Soy contains a type of estrogen that is bad for females in excess because it messes with your hormones. Use a protein shake that is from the store if you are doing a liquid diet. Muscle milk is the best. I don't like them since natural food is the best but if you are doing this for just 3 days go to your health store and buy 3 servings of Muscle milk. Don't drink so much water. You are not eating enough salt with your diet so you can actually kill yourself this way. With so much liquid just consume about 1-2 normal water bottles. Please please don't do this more than 3 days. You are depriving your body of certain nutrients but your body will be fine with what you have. Just make sure you use plenty of veggies and not just a few of leaves. Also don't exercise a ton on this diet. It will not sustain much activity. So just 20 minutes of walking is fine. Once you are eating normally you can increase your exercise.