How to get more weight if i'm eating a lot and still losing or stay in the same weight with 29years old and 69kg?

First - see your DR: to ensure that their isn't a medical reason for your weight loss. Eat healthy high calorie foods. Eat 6 meals/day. Work on strength training to build large muscle groups. Workout w heavier weights w fewer repetitions. Sleep at least 8 to 9 hrs/night. Hydrate well w water. Foods to help w healthy weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, Avocados, granola