There are five basic exercises that you can do to heal and reclaim your inner child, according to John Bradshaw. These are:
1. Describe your home and yourself through your developmental stages (as an infant, as a toddler, as a pre-schooler, school-age and as an adolescent)
2. Write a letter to your inner child at each stage
3. Write a letter from your inner child at each stage
4. Do a meditation where you meet yourself and your memories
5. Say affirmations according to each stage (here having someone else to partner with is recommended)
Like with all healing, it's about returning to what is whole from the beginning and a natural process, when we let it. Each step a practice of self-compassion and correction. Have you tried?