My 3years old daughter, who is very talkative at home but silent when we meet others and at school. She has been going to playschool from 18 months old but hasn’t spoke with her teachers atleast once. She play and talk with her friends. Enjoy going to school but doesn’t talk to teachers and elders. She speaks well with her grandparents , Aunty and uncles but not with new people . Seriously need help on this,
This sounds like anxiety manifesting as situational mutism.
Formerly called "selective mutism," situational mutism is a stress response akin to freeze (as in fight, flight, freeze, fawn, flop, and brace). It's very common in autistic people. The important thing to remember is not to punish your child for not talking or to force them to speak when they aren't ready. In those moments of anxiety, they are likely feeling vulnerable and need assistance in feeling safe again.
To start, I recommend completing this assessment of lagging skills and unsolved problems worksheet. The bottom section titled "Unsolved Problems" is where you'll describe the most recent time your daughter struggled to talk to a teacher.
Even though she's 3, you mentioned she's rather talkative, so after completing the worksheet, I'd suggest trying Dr. Ross Greene's Plan B method for figuring out the underlying cause.
With my own daughter, we handled it with an occupational therapist that helped us learn emotional regulation techniques, including deep pressure therapy. For us specifically, we used deep belly breaths, big/tight hugs, hugging self, and hugging a lovey (favorite stuffed animal). This, coupled with some extra time to comfortably transition, allowed my daughter to come out of her anxious spiral sooner.
If we rush or skip these accommodations, it leads to a dysregulated and emotional kid.