The sudden loss of libido may be caused by psychological factors, hypothyroidism, endocrine disorders, physical illnesses and so on. 1. Psychological factors: If a couple is usually under too much psychological pressure, too busy at work every day, mental tension, etc., it may lead to psychological disorders, fear of sexual desire, causing a sudden loss of libido. 2. Hypothyroidism: If you suffer from hypothyroidism, it will easily lead to insufficient synthesis and secretion of thyroid hormones by thyroid cells, causing low metabolism of all tissues and organs in the whole body and a corresponding decrease in their functions, which will lead to a sudden loss of libido. 3. Endocrine disorders: If endocrine disorders occur, it may affect the normal function of the body, causing neuromodulation dysfunction, and a sudden loss of libido. 4. Physical disease: If a woman suffers from pelvic inflammation, vaginal inflammation, or a man has prostatitis, epididymitis and other diseases, it may lead to a sudden loss of libido. If you have no sex drive, you should go to the hospital in time to get a clear explanation of the cause and then give appropriate treatment and therapy under the guidance of the doctor.