Wife not allowing to see my Children

Dear Sir/ Madam - We have completed 10 yrs of marriage life , we have 2 kids - a Boy of 6.8 yrs and Girl of 4.1 yrs , last 8 months wife staying separately near to her job place and took the children also with her, saying our house is far from job location 24 kilometers only and weekend they will visit our house. But last 40 days they did not come and she moved to a new house near to her mother's place and started to hide my children not allowing me to see or call through phone. I dont have any bad habits and was taking care my familly well,But her plan is she wants to forsake my old sick mother 72yrs and come with here separately to a rent house. Now slowly she is threatening that she is going to divorce,she is saying she dont want me , she want only the kids going to live separately. How can i see my children as per the law.May be wife doesn't want Husband as she is selfish, but Children needs father and father needs Children, Without father children will not come, both mother and father are needed to children as they are ignorant, she and her mother hiding them in a separate house . Its sad father cannot do anything to his loving children, Even i want both mother and children , but wife started hating me and her brother and mother n law making her to think on divorce. Kindly Advocates provide your valuable suggestion.