This may be a vague question, so I apologize in advance. I have a tamarind sapling approximately 1.5 years old that I started from a seed. It's been grown indoors since I live in the northeastern US, and I've kept it under lights since it was in a dark corner of the room. It seemed to be thriving, growing new leaves and even branches.
I've recently moved, and placed it near a window(north facing) and didn't set up any lights, thinking that the natural light from the window would be sufficient. I also held off watering all my plants for a couple weeks so they can get adjusted to their new location(I only water after the soil usually dries out anyway, which is usually after about a week).
When I finally went to water it (2 weeks since the last watering) I noticed all the leaves were kind of droopy. I also noticed some shedding. I thought, oh crap I waited too long to water it, and gave it some hoping it would bounce back. Over the next couple days I noticed more and more shedding, and when I shook the plant, more and more leaves fell off. Today it's mostly bare, save for maybe about 10 leaves.