I feel better now, had a stomach virus for 3 days. I still feel nauseous and I feel like I wont ever get my appetite back. How long does it take?

Road to recovery. Well it's great you're feeling better. Certainly some viruses are nastier than others. Because of your young age -I would expect you to continue to improve by leaps and bounds. To speed things along, be kind to yourself -try to rest/sleep, eat simple foods (chicken soup), avoid stress and toxins (smoke, alcohol). I like ginger tea for nausea-try boiling water with a chunk of ginger x10 min, +honey.