Single dose of lorazepam would have made. no effect on your ability to have erection or on your body. There is absolutely no need to be worried and concern about the lorazepam pill. However, do not try doing that again as taking any medication against he advice or without consulting a doctor can be harmful and may have serious side effect. If you are concern about anxiety and erection problem, you can consult with a sexologist. You can also ask a direct query to me here on Practo as well. A detailed information about your problem is needed. An underlying anxiety problem can be suspected. Most importantly, you must understand that there is cure available, but it should only be on an advice of an expert.
Next Steps
Kindly send a detailed query here on Practo.