Hesitating to talk to people. Guidance.

My gal s not at all talking a wrd to her teachers or other students. In home, she s talking nonstop. The same hesitation she s having wid new ppl also. She s not even telling her name, not responding to attendance call, not saying gud mrng or bye to teachers while leaving. Even if she needs to use toilet, she s askng through signs.  These are the complaints we hv received from her teacher. She s having good academic skills and getting full marks in tests. But when it comes to oral test, she gets zero. Ths s vry concerning that We r trying to make her communicate and failing continuously. She is not talking to her teachers at any serious cost. If we ask whether she likes them, she is telling yes. We cant figure out what is the issue and hw we can treat her. Sometimes, am losing my temper hearing complaints daily from school. She s a single child, and am wrking from home and available for her anytime not to make her feel lonely. Expecting ur kind guidance.