Can you tell me the therapy needed for a lumbar ache?

Core exercises. You can perform all kinds of stretches for the core muscles (abdominal & back area) as well as as the extremities. Low back pain is typically made worse with deep bending of the lumbar spine or flexion of the hips (bringing your knees up towards your head). Do these exercises slowly and you should improve your range of motion and pain slowly. Seek medical attention if the symptoms last > 10 days.
Several. Lifestyle changes are important like not smoking, weight control and regular exercise. You can use medication if no contraindications like ibuprophen or naproxen, try a back support, guided exercise & activity modification. Exercise includes stretching, core muscle strengthening and cardiovascular workouts. If no better, then see your doctor for further evaluation and treatment.