Anhidrosis is what this is called. It could be from :
skin diseases that block sweat glands
congenital disorders including as ectodermal dysplasia
some drugs
trauma to sweat glands
burns
dehydration
When I was taking a physical activity class, the instructor said that if anhidrosis is caused from blockages due to lotions that are filled with chemicals, or drugs that you have taken, then vigorous physical activity and lots of clean water can reveres this. However, it is a different story if this is from trauma or skin disease.
Trash all your lotions and body product; do some research on the drugs you may be currently taking.