While I can’t be 100% certain, I think this is a psychological issue. I believe what happened was that you tried to masturbate one time and for some reason, it didn’t work. Maybe something happened during the day that bothered you or you were tired. It doesn’t matter what it was, but you tried to masturbate and you couldn’t have an orgasm. Then the next time you tried, you remembered that you failed the last time, and started to worry that you’d fail again. That created a situation where you couldn’t have an orgasm once again, and then it became a vicious cycle. If that’s what is going on, then you just have to find a way to push those worries away. Using a very strong sexual fantasy might occupy your brain sufficiently to accomplish that. Whatever you do, don’t put added pressure on yourself because that’s just going to aggravate matters. Perhaps just taking a break from masturbation for a time would also do the trick. If nothing works and you’re feeling very sexually frustrated, then you could make an appointment to see a sex therapist. But first, try to stop this cycle by pushing those worries out of your mind when you masturbate.