My employer no allow me to go back my country and keep my passport under his custady

Dear Sir,

I am Kathiravel Surendran who has been working in china Guanzhou for one year , Now I want to go back my country as my child physical is quite serious . but my employer no allow me to go and keep my passport under his custady. please advise me how to handle this problem

Yours faithfully,

K.Surendran