Impotence is not because of masturbation. rather then masturbation is good for sexual health.It prevents sexual transmitted diseases.

You will need to get blood work done to see where your hormonal profile is so that you will no what hormones to replace to heal. Since you are just 24 there is still a slight chance you may be able to heal with abstinence. Set yourself an ejaculation frequency of about once every week to 2 weeks eat a good diet get 8 to nine hours sleep and do about 20 minutes of cardio 3 days a week for 6 months and your erections should go back to rock hard if not see an endocrinologist.