Don’t panic! Even if you haven’t trained for a longer time or just from time to time, you can return to your old form within a few weeks.
Your body remembers
Your body can “remember” its old form and even after a long break from training, your body knows its old good shape and that’s why you can return to your old shape.
I learned for myself that after a break you should not continue on the same level of training where you stopped. Start with fun and ease.
Take a serious look on your eating habits. Often athletes eat the same amount although they don’t do regular sports any more.