I am very sorry about your child. It is possible to reverse a vasectomy, please discuss it with your doctor or a urologist. A lot will depend on the age of your wife also.
Vasectomy reversal is an option but they are a big surgery compare to a vasectomy. You should really consult with a urologist about the reversal or maybe having a biopsy and having your sperm frozen. I'm sorry to hear about you loosing your child.