Both posters gave you good advice. Most people look for an overnight magic bulletin to cure themselves. It took you a long time to get where you are today. It will take that long to be healthy and vibrant.
If you decide to fast....
Nothing but water, no supplements, no teeth brushing, chewing gum, teas, etc.
Drink warm filtered water as per thirst.
Rest plenty, your body needs energy to heal.
30-40 day fast is hefty goal. Perhaps you can try short fasts, which I think you done before.
Eating raw vegan diet would be ideal, but you can eat some steamed and baked veggies. No processed junk from packages, which probably made you ill and over weight.