I'm 29 years old but still I don't have a beard. What can I do to let it grow naturally?

Facial hair or having a beard is a genetic trait.  There are no medication to grow a beard. One option is facial hair transplant

In order to solve this issue you have to figure out the problem first. After you find the reason why your beard is not growing you can take vitamin B as a support.

Beard area may restored with HT. You may have  a hair transplant surgery from scalp skin follicular units to beard area with FUE to have facial beard hair.If the patient needs a full face transplantation, at least 3000-3500 grafts would better to harvest and transplant to cheek, mustache areas.