Ok, I started an avocado tree from an avocado seed. It took about 2 and a half months to sprout. It finally started getting leaves a few weeks ago, and was coming along fine, but then I don't know what happened, the leaves started curling up and it happened almost over night. I've kept the soil moist. I've included a photo. Maybe someone could tell me what went wrong or what I did wrong? Thank you for your feedback.

P.S. (It's more of a decorative plant/tree. I know it won't yield any fruit).