Hello!
Welcome!
If your weight gain is fairly sudden and unexplained, you might consider going to your doctor to make sure your health is otherwise in good shape. Sometimes an issue with another part of the body, such as the thyroid, can cause weight gain.
Why don't you give us an idea of what you're eating on an average day? Do you have an eating plan for losing weight? If so, tell us more about it and that'll give us more information.
Also, there's a lot of good information on this site both in active threads and in old ones.