Ashwagandha alone does not help in increasing height. It acts like a general tonic. Some combinatiins of ayurvedic medicine will help you.
Next Steps
But for proper medication you should preferably visit an ayurvedic physician as your proper case history will have to be taken. Take a protein rich diet with exercises like jogging and stretching. Surya namaskars also help.
Health Tips
take proteins only under proper supervision and only if you exercise adequately