Currently my lo is very closed to my helper. How to bring the bond back?

Simply spend more time with your kid. I know it hurts when your own kid reaches for another adult than their mother. I've experienced this with my own daughters. Start with fun activities so your child will associate time with you as time for fun. Then gradually do the things that he usually does with the helper, like bathing, feeding, etc. You'll be surprised that it'll only take a short time before your little one will feel close to you again.