Try eating comfort food such as ice cream. If this doesn’t pick up your spirits you may need professional help. Do not self medicate through drugs or alcohol. Speak to your rabbi or doctor, they may better advise you. Therapist will help you understand your problem but wouldn’t cure you as they want you to continue coming as a patient.
If you want a Torah solution then you should consult a rabbi. Many times your goals are set to high and you feel that you are not succeeding as well as others. Or maybe g-d wants you to succeed in another field.