I have no emotions. What's wrong with my brain chemistry?

Depression . May have depression. Whoever you see , keep in mind meds should be used for at least 9 months, see a psychologist (regular pcp don't resources for psychotherapy), see clergy, get support from a good friend or family, meditate. It is a marathon. Stick with the same doctor.
Trauma? One symptom of post-trauma stress disorder is numbing or feeling like one doesn't have any feelings. Another possibility is that growing up you did not receive the psychological space to have feelings as a child and consequently you don't know what you are feeling. This can also be a side effect of medication or being in shock from a loss of a loved one/ grief. Some ideas to consider.