I want to find an old friend who has lost contact for more than 20 years and is also a good sister. Her name is Mao, and she is from Guoyang County, Anhui Province. I don't know how to find her

Long-lost old friends need a complicated search process. Because we have lost contact for more than 20 years, some place names have changed, and it is possible that the house will be demolished. If there is no good way to find them, I'm afraid it will be difficult to find them. But one's place of origin cannot be changed. You can ask her village (neighborhood Committee) where she is, or ask the police station where she lives.